U.S. patent application number 16/581766 was filed with the patent office on 2020-01-16 for communication control apparatus and wireless communication apparatus.
This patent application is currently assigned to Sony Corporation. The applicant listed for this patent is Sony Corporation. Invention is credited to Sho FURUICHI, Ryota KIMURA, Ryo SAWAI, Hiromasa UCHIYAMA, Takashi USUI.
Application Number | 20200022092 16/581766 |
Document ID | / |
Family ID | 52483390 |
Filed Date | 2020-01-16 |
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United States Patent
Application |
20200022092 |
Kind Code |
A1 |
FURUICHI; Sho ; et
al. |
January 16, 2020 |
COMMUNICATION CONTROL APPARATUS AND WIRELESS COMMUNICATION
APPARATUS
Abstract
[Object] To achieve both prevention of harmful interference and
promptness of power allocation under conditions in which multiple
secondary systems may be managed. [Solution] Provided is a
communication control apparatus including: a calculation unit
configured to calculate a transmit power to be allocated, including
a nominal transmit power and a margin for interference avoidance,
for one or more secondary systems that secondarily use frequency
channels protected for a primary system; and a determination unit
configured to determine a variation in a number of secondary
systems, and cause the calculation unit to adjust the margin for
interference avoidance on a basis of the determined variation.
Inventors: |
FURUICHI; Sho; (Tokyo,
JP) ; SAWAI; Ryo; (Tokyo, JP) ; KIMURA;
Ryota; (Tokyo, JP) ; UCHIYAMA; Hiromasa;
(Tokyo, JP) ; USUI; Takashi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sony Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Sony Corporation
Tokyo
JP
|
Family ID: |
52483390 |
Appl. No.: |
16/581766 |
Filed: |
September 25, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15978624 |
May 14, 2018 |
10448341 |
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16581766 |
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14895160 |
Dec 1, 2015 |
10004044 |
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PCT/JP2014/066410 |
Jun 20, 2014 |
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15978624 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 52/386 20130101;
H04W 72/082 20130101; H04B 17/345 20150115; H04W 52/143 20130101;
H04W 52/228 20130101; H04W 52/362 20130101; H04W 52/343 20130101;
H04B 17/373 20150115; H04W 52/243 20130101; H04W 52/244
20130101 |
International
Class: |
H04W 52/24 20060101
H04W052/24; H04W 72/08 20060101 H04W072/08; H04W 52/38 20060101
H04W052/38; H04W 52/36 20060101 H04W052/36; H04B 17/373 20060101
H04B017/373; H04W 52/34 20060101 H04W052/34; H04W 52/14 20060101
H04W052/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 21, 2013 |
JP |
2013-171018 |
Claims
1. (canceled)
2. A communication control apparatus comprising: circuitry
configured to: allocate a transmit power for one or more secondary
systems that secondarily use frequency channels allocated to a
primary system; monitor activation requests received from the one
or more secondary systems; determine a variation in a number of one
or more master devices which belong to a secondary system, wherein
the master devices are configured to operate according to a
time-division scheme and communicate with slave devices that are
configured to operate the same scheme; estimate an interference
level from the secondary systems to the primary system when the
variation in the number of the one or more master devices is
greater than a threshold value; and signal information indicating
that an activation request is allowed to the one or more secondary
systems.
3. The communication control apparatus according to claim 2,
wherein the circuitry is further configured to periodically
calculate the transmit power for the one or more secondary
systems.
4. The communication control apparatus according to claim 2,
wherein the circuitry is further configured to calculate the
transmit power for the one or more secondary systems based on
information reported by the one or more secondary systems.
5. The communication control apparatus according to claim 2,
wherein the circuitry is further configured to: determine a method
to adjust the allocated transmit power according to a condition
dependent on the number of one or more secondary systems; determine
whether to recalculate a previously calculated transmit power or
adjust the previously calculated transmit power by adjusting a
margin for interference avoidance based on the variation; and
adjust the allocated transmit power based on the determined
method.
6. The communication control apparatus according to claim 5,
wherein the circuitry is further configured to recalculate the
previously calculated transmit power in a case of variation in a
number of one or more secondary systems falling below a threshold
value, and adjust the previously calculated transmit power in
another case of the variation in the number of one or more
secondary systems exceeding the threshold value.
7. The communication control apparatus according to claim 6,
wherein the threshold value is configured in advance in a manner
that an estimated calculation time dependent on the number of one
or more secondary systems does not exceed an allowed calculation
time.
8. The communication control apparatus according to claim 6,
wherein the threshold value is configured dynamically in a manner
that an estimated calculation time dependent on the number of one
or more secondary systems does not exceed an allowed calculation
time.
9. A communication method comprising: allocating, by circuitry, a
transmit power for one or more secondary systems that secondarily
use frequency channels allocated to a primary system; monitoring
activation requests received from the one or more secondary
systems; determining a variation in a number of one or more master
devices which belong to a secondary system, wherein the master
devices are configured to operate according to a time-division
scheme and communicate with slave devices that are configured to
operate the same scheme; estimating an interference level from the
secondary systems to the primary system when the variation in the
number of the one or more master devices is greater than a
threshold value; and signaling information indicating that an
activation request is allowed to the one or more secondary
systems.
10. The communication method according to claim 9, further
comprising: periodically calculating the transmit power for the one
or more secondary systems.
11. The communication method according to claim 9, further
comprising: calculating the transmit power for the one or more
secondary systems based on information reported by the one or more
secondary systems.
12. The communication method according to claim 9, further
comprising: determining a method to adjust the allocated transmit
power according to a condition dependent on the number of one or
more secondary systems; determining whether to recalculate a
previously calculated transmit power or adjust the previously
calculated transmit power by adjusting a margin for interference
avoidance based on the variation; and adjusting the allocated
transmit power based on the determined method.
13. The communication method according to claim 12, further
comprising: recalculating the previously calculated transmit power
in a case of variation in a number of one or more secondary systems
falling below a threshold value; and adjusting the previously
calculated transmit power in another case of the variation in the
number of one or more secondary systems exceeding the threshold
value.
14. The communication method according to claim 13, wherein the
threshold value is configured in advance in a manner that an
estimated calculation time dependent on the number of one or more
secondary systems does not exceed an allowed calculation time.
15. The communication method according to claim 13, wherein the
threshold value is configured dynamically in a manner that an
estimated calculation time dependent on the number of one or more
secondary systems does not exceed an allowed calculation time.
16. A non-transitory computer-readable storage medium storing
executable instructions which, when executed by circuitry, cause
the circuitry to perform a communication method, the method
comprising: allocating a transmit power for one or more secondary
systems that secondarily use frequency channels allocated to a
primary system; monitoring activation requests received from the
one or more secondary systems; determining a variation in a number
of one or more master devices which belong to a secondary system,
wherein the master devices are configured to operate according to a
time-division scheme and communicate with slave devices that are
configured to operate the same scheme; estimating an interference
level from the secondary systems to the primary system when the
variation in the number of the one or more master devices is
greater than a threshold value; and signaling information
indicating that an activation request is allowed to the one or more
secondary systems.
17. The non-transitory computer-readable storage medium according
to claim 16, wherein the method further comprises: periodically
calculating the transmit power for the one or more secondary
systems.
18. The non-transitory computer-readable storage medium according
to claim 16, wherein the method further comprises: calculating the
transmit power for the one or more secondary systems based on
information reported by the one or more secondary systems.
19. The non-transitory computer-readable storage medium according
to claim 16, wherein the method further comprises: determining a
method to adjust the allocated transmit power according to a
condition dependent on the number of one or more secondary systems;
determining whether to recalculate a previously calculated transmit
power or adjust the previously calculated transmit power by
adjusting a margin for interference avoidance based on the
variation; and adjusting the allocated transmit power based on the
determined method.
20. The non-transitory computer-readable storage medium according
to claim 19, wherein the method further comprises: recalculating
the previously calculated transmit power in a case of variation in
a number of one or more secondary systems falling below a threshold
value; and adjusting the previously calculated transmit power in
another case of the variation in the number of one or more
secondary systems exceeding the threshold value.
21. The non-transitory computer-readable storage medium according
to claim 20, wherein the threshold value is configured in advance
in a manner that an estimated calculation time dependent on the
number of one or more secondary systems does not exceed an allowed
calculation time.
22. The non-transitory computer-readable storage medium according
to claim 20, wherein the threshold value is configured dynamically
in a manner that an estimated calculation time dependent on the
number of one or more secondary systems does not exceed an allowed
calculation time.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 15/978,624, filed May 14, 2018, which is a
continuation of U.S. application Ser. No. 14/895,160, filed on Dec.
1, 2015 (now U.S. Pat. No. 10,004,044), which is based on PCT
application No. PCT/JP2014/066410, filed on Jun. 20, 2014, and
claims priority to Japanese Patent Application 2013-171018, filed
on Aug. 21, 2013, the entire contents of each of which is
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a communication control
apparatus and a wireless communication apparatus.
BACKGROUND ART
[0003] The secondary usage of frequencies is being discussed as one
countermeasure for relieving the depletion of frequency resources
in the future. Secondary usage of frequencies refers to another
system secondarily using some or all of the frequency channel
preferentially allocated to a first system. Generally, the system
to which the frequency channel is preferentially allocated is
called the primary system, while the system that secondarily uses
the frequency channel is called the secondary system. A typical
example of a secondary system is a cognitive radio system.
[0004] TV white spaces are an example of frequency channels whose
secondary usage is being discussed (see Non-Patent Literature 1).
TV white spaces refer to channels, from among the frequency
channels allocated to a television broadcasting system that acts as
a primary system, which are not being used by that television
broadcasting system depending on the geographical area. By opening
up these TV white spaces to secondary systems, efficient frequency
resource utilization may be realized. Non-Patent Literature 1
defines the technical requirements and operational requirements of
a white space device (WSD) using a secondary system. A device that
manages a secondary system is also called a master WSD, while a
device that participates in a secondary system is also called a
slave WSD.
[0005] During secondary usage of a frequency band, the secondary
system ordinarily is demanded to be operated so as not to exert
harmful interference on the primary system. One important
technology for this purpose is transmit power control. For example,
Patent Literature 1 and Patent Literature 2 disclose technology for
restraining the aggregated interference that multiple secondary
systems exert on the primary system to an allowed level.
CITATION LIST
Patent Literature
[0006] Patent Literature 1: JP 2012-151815A [0007] Patent
Literature 2: JP 2013-78096A
Non-Patent Literature
[0007] [0008] Non-Patent Literature 1: ECC Electronic
Communications Committee), "Technical and operational requirements
for the operation of white space devices under geo-location
approach", ECC REPORT 186, January 2013
SUMMARY OF INVENTION
Technical Problem
[0009] However, the calculation cost for evaluating the aggregated
interference exerted on the primary system increases as the number
of secondary systems increases. For example, if the number of
master WSDs secondarily using the white space for the same primary
system doubles, the calculation cost may quadruple. If the
calculation for interference evaluation does not finish within an
allowed time, power allocation is unable to track variation in the
number of secondary systems, and the validity of control possibly
may be lost.
[0010] Consequently, it is desirable to realize a mechanism capable
of achieving both prevention of harmful interference and promptness
of power allocation under conditions in which multiple secondary
systems may be managed.
Solution to Problem
[0011] According to the present disclosure, there is provided a
communication control apparatus including: a calculation unit
configured to calculate a transmit power to be allocated, including
a nominal transmit power and a margin for interference avoidance,
for one or more secondary systems that secondarily use frequency
channels protected for a primary system; and a determination unit
configured to determine a variation in a number of secondary
systems, and cause the calculation unit to adjust the margin for
interference avoidance on a basis of the determined variation.
[0012] According to the present disclosure, there is provided a
communication control apparatus including: a communication unit
configured to communicate with a master device of one or more
secondary systems that secondarily use frequency channels protected
for a primary system; and a control unit configured to signal, on a
basis of information acquired from a data server that calculates an
allocated transmit power for the secondary systems including a
nominal transmit power and a margin for interference avoidance
adjusted on a basis of variation in a number of secondary systems,
parameters for specifying the allocated transmit power to the
master device via the communication unit.
[0013] According to the present disclosure, there is provided a
wireless communication apparatus that operates and manages a
secondary system that secondarily uses a frequency channel
protected for a primary system, the wireless communication
apparatus including: a communication unit configured to receive
signaling of parameters for specifying an allocated transmit power
based on information acquired from a data server that calculates
the allocated transmit power for the secondary system including a
nominal transmit power and a margin for interference avoidance
adjusted on a basis of variation in a number of secondary systems;
and a communication control unit configured to control wireless
communication between the wireless communication apparatus and one
or more terminal apparatuses according to the allocated transmit
power specified using the parameters.
Advantageous Effects of Invention
[0014] According to the technology in accordance with the present
disclosure, it is possible to achieve both prevention of harmful
interference prevention and promptness of power allocation under
conditions in which multiple secondary systems may be managed.
[0015] Note that the effects described above are not necessarily
limited, and along with or instead of the effects, any effect that
is desired to be introduced in the present specification or other
effects that can be expected from the present specification may be
exhibited.
BRIEF DESCRIPTION OF DRAWINGS
[0016] FIG. 1 is an explanatory diagram for describing an overview
of a communication control system according to an embodiment.
[0017] FIG. 2 is an explanatory diagram for describing an example
of a scenario in which secondary systems increase.
[0018] FIG. 3 is an explanatory diagram for describing another
example of a scenario in which secondary systems increase.
[0019] FIG. 4 is a graph illustrating an example of the
relationship between the number of secondary systems and the
calculation cost of transmit power to allocate.
[0020] FIG. 5 is an explanatory diagram for describing an example
of delayed power allocation.
[0021] FIG. 6 is a block diagram illustrating an example of a
logical configuration of a communication control apparatus
according to an embodiment.
[0022] FIG. 7A is a flowchart illustrating a first example of the
flow of a power distribution process according to an
embodiment.
[0023] FIG. 7B is a flowchart illustrating a second example of the
flow of a power distribution process according to an
embodiment.
[0024] FIG. 7C is a flowchart illustrating a third example of the
flow of a power distribution process according to an
embodiment.
[0025] FIG. 7D is a flowchart illustrating a fourth example of the
flow of a power distribution process according to an
embodiment.
[0026] FIG. 8 is a flowchart illustrating an example of the flow of
a margin adjustment process which may be executed during the power
distribution process illustrated in FIGS. 7A to 7C.
[0027] FIG. 9A is a first sequence diagram illustrating an example
of a signaling sequence in a system according to an embodiment.
[0028] FIG. 9B is a second sequence diagram illustrating an example
of a signaling sequence in a system according to an embodiment.
[0029] FIG. 10 is a block diagram illustrating an example of a
logical configuration of a wireless communication apparatus
according to an embodiment.
[0030] FIG. 11 is an explanatory diagram for describing another
example of a system model.
[0031] FIG. 12 is a block diagram illustrating an example of a
schematic configuration of a GLDB.
[0032] FIG. 13 is a block diagram illustrating an example of a
schematic configuration of an eNB.
[0033] FIG. 14 is a block diagram illustrating an example of a
schematic configuration of a smartphone.
[0034] FIG. 15 is a block diagram illustrating an example of a
schematic configuration of a car navigation apparatus.
DESCRIPTION OF EMBODIMENTS
[0035] Hereinafter, (a) preferred embodiment(s) of the present
disclosure will be described in detail with reference to the
appended drawings. In this specification and the drawings, elements
that have substantially the same function and structure are denoted
with the same reference signs, and repeated explanation is
omitted.
[0036] Also, the description will proceed in the following order.
[0037] 1. Overview of system [0038] 1-1. System model using GLDB
[0039] 1-2. Change in number of secondary systems [0040] 1-3.
Delayed power allocation [0041] 2. Examples of power calculation
model [0042] 2-1. Existing technique [0043] 2-2. Simpler technique
[0044] 3. Exemplary configuration of communication control
apparatus [0045] 3-1. Component configuration [0046] 3-2.
Modifications [0047] 4. Process flows [0048] 4-1. Power
distribution process [0049] 4-2. Margin adjustment process [0050]
4-3. Signaling sequence [0051] 5. Exemplary configuration of
wireless communication apparatus [0052] 6. Another example of
system model [0053] 7. Applications [0054] 7-1. Example application
related to communication control apparatus [0055] 7-2. Example
application related to wireless communication apparatus [0056] 8.
Conclusion
1. OVERVIEW OF SYSTEM
1-1. System Model Using GLDB
[0057] FIG. 1 is an explanatory diagram for describing a summary of
a communication control system 1 according to an embodiment of
technology in accordance with the present disclosure. The
communication control system 1 includes a primary transceiver 10,
one or more wireless communication apparatuses 20a, 20b, and so on,
and a communication control apparatus 100.
[0058] The primary transceiver 10 is a transceiver installed to
manage a primary system on a frequency channel that has been
legally licensed or assigned usage rights. The primary transceiver
10 transmits wireless signals of the primary system to primary
terminals (not illustrated) positioned inside a service area 11.
The primary system may be a television broadcasting system such as
a Digital Video Broadcasting--Terrestrial (DVB-T) system, for
example. In this case, a primary receiver is a receiver including a
television antenna and a tuner (also called an incumbent receiver).
Additionally, the primary system may also be a mobile communication
system that operates in accordance with a communication scheme such
as LTE, LTE-A, GSM, UMTS, W-CDMA, CDMA200, WiMAX, WiMAX 2, or IEEE
802.16. Additionally, the primary system may also be another type
of wireless communication system such as an aircraft radio system
(for example, the Aeronautical Radio Navigation Service
(ARNS)).
[0059] The primary transceiver 10 is connected to a core network
15. The core network 15 includes multiple control nodes that
respectively have roles such as user information management,
terminal mobility management, packet forwarding and gateway.
[0060] Each of the wireless communication apparatuses 20a, 20b, and
so on is a master device that manages a secondary system by
secondarily using a frequency channel protected for the primary
system. Each of the wireless communication apparatuses 20a, 20b,
and so on may be the master WSD described in Non-Patent Literature
1, for example, or some other type of device, such as a small-cell
base station or a wireless access point. Small cells may include
femtocells, nanocells, picocells, microcells, and the like.
[0061] Note that in this specification, when the wireless
communication apparatuses 20a, 20b, and so on are not being
distinguished from each other, these apparatuses will be
collectively referred to as the wireless communication apparatus 20
by omitting the trailing letters of the reference signs. This
applies similarly to the other structural elements.
[0062] The wireless communication apparatus 20 transmits and
receives wireless signals to and from a slave device (not
illustrated) positioned near the wireless communication apparatus
20 itself. When the secondary system exists in the vicinity of the
service area 11, the wireless signals of the secondary system
interfere with the primary terminals. When multiple secondary
systems exist as in the example of FIG. 1, the interference
observed at a primary terminal may be aggregated.
[0063] The wireless communication apparatus 20 connects to a packet
data network (PDN) 16 via backhauling. The backhauling may be a
wired link or a wireless link. The PDN 16 connects to the core
network 15 via a gateway (not illustrated).
[0064] The communication control apparatus 100 is a data server
disposed on the PDN 16. The communication control apparatus 100 may
be the geo-location database (GLDB) described in Non-Patent
Literature 1, for example, or some other type of server. The
communication control apparatus 100 is not limited to the example
of FIG. 1, and may also be disposed on the core network 15. Also, a
functional entity including functions similar to the communication
control apparatus 100 may also be implemented in the primary
transceiver 10. The communication control apparatus 100 allows
transmit power to each secondary system so that the aggregated
interference caused by wireless signals from one or more secondary
systems does not exert harmful effects on the primary system. For
example, the wireless communication apparatus 20, which is the
master device of each secondary system, transmits an activation
request to the communication control apparatus 100 via backhauling
when starting the operation and management of the system. The
communication control apparatus 100, in response to receiving the
activation request, calculates the transmit power that should be
allocated to each secondary system. Subsequently, the communication
control apparatus 100 notifies the wireless communication apparatus
20 of the transmit power allocation result (as well as other
information, such as a list of channels available for use). Through
such a procedure, the operation and management of secondary systems
become possible.
[0065] Typically, the aggregated interference caused by wireless
signals from secondary systems is estimated as an interference
level at some location (called a reference point) inside the
service area 11. Subsequently, the communication control apparatus
100 calculates the transmit power to allocate to each secondary
system so that the estimated interference level does not exceed an
allowed level. The reference point may also be a location on a
protection contour of the service area 11 where the distance from
each wireless communication apparatus 20 is the shortest, for
example. Alternatively, the reference point may also be the
location where the primary terminal the shortest distance away from
each wireless communication apparatus 20 is present. In the example
of FIG. 1, the reference points 22a, 22b, and so on corresponding
to each of the wireless communication apparatuses 20a, 20b, and so
on are configured on a protection contour of the service area
11.
[0066] For example, the power distribution method described in
Patent Literature 1 or the margin minimization method (a technique
using a flexible minimized margin) described in Non-Patent
Literature 2 has the advantage of being able to allocate a larger
transmit power to a secondary system as a result of configuring as
small a margin for interference avoidance as possible, and thus
raise the throughput of the secondary system. However, with these
techniques, since the aggregated interference is evaluated at all
reference points, the calculation cost for calculating the transmit
power to allocated increases as the number of secondary systems
increases. In the simplest example, the calculation cost may
increase on the order of the square of the number of secondary
systems (the product of the number of reference points and the
number of secondary systems). Additionally, if factors such as the
process for the configuration of the reference points and the
signaling overhead are also considered, the calculation cost for
calculating the transmit power to allocate becomes
non-negligible.
1-2. Change in Number of Secondary Systems
[0067] A change in the number of secondary systems may occur due to
various factors. For example, referring to FIG. 2 in contrast to
FIG. 1, the wireless communication apparatuses 20h, 20i, and 20j
are newly included in the communication control system 1. Each of
the wireless communication apparatuses 20h, 20i, and 20j is also a
master device that operates and manages a secondary system. As a
result, the number of secondary systems increases from six to nine.
The wireless communication apparatuses 20h, 20i, and 20j may be
devices that moved from another place to the vicinity of the
service area 11, or devices that returned from sleep mode to active
mode. In the recent mobile environment with a wide proliferation of
mobile devices in which fine-grained sleep control is often desired
for power savings, such changes in the number of secondary systems
occur frequently. Consequently, it is desirable for the allocation
of transmit power to secondary systems to be capable of adequately
tracking changes in the number of secondary systems.
[0068] The left half of FIG. 3 illustrates a primary transceiver
10a that operates and manages a primary system inside a service
area 11a in a geographical region 3a. A communication control
apparatus 100a has the authority to allocate transmit power to one
or more secondary systems that secondarily use a frequency channel
for the purpose of the primary transceiver 10a inside the
geographical region 3a. The right half of FIG. 3 illustrates a
primary transceiver 10b that operates and manages a primary system
inside a service area 11b in a geographical region 3b. A
communication control apparatus 100b has the authority to allocate
transmit power to one or more secondary systems that secondarily
use a frequency channel for the purpose of the primary transceiver
10b inside the geographical region 3b. Herein, depending on the
positional relationships of devices between the regions or the
conditions of transmit power allocation, there is a possibility
that the communication control apparatus 100a may need to account
for interference signals from secondary systems inside the
geographical region 3b. In such cases, the number of secondary
systems that must be introduced into the power allocation
calculation may also increase.
[0069] FIG. 4 is a graph illustrating an example of the
relationship between the number of secondary systems and the
calculation cost of transmit power to allocate. The horizontal axis
of FIG. 4 indicates the number of active primary WDSs, or in other
words the number of secondary systems that must be introduced into
the power allocation calculation. The vertical axis of FIG. 4
indicates the calculation cost of power allocation as estimated
according to a certain simulation model. As FIG. 4 demonstrates,
the calculation cost increases as the number of master devices of
secondary systems becomes larger.
1-3. Delayed Power Allocation
[0070] As discussed above, it is desirable for the allocation of
transmit power to secondary systems to be capable of adequately
tracking changes in the number of secondary systems. However, if
the calculation cost becomes great, there is a risk that the power
allocation calculation may not finish within a designated
calculation period, and the allocation of transmit power becoming
may become delayed.
[0071] FIG. 5 is an explanatory diagram for describing an example
of delayed power allocation. In the example of FIG. 5, the
calculation of power allocation is executed periodically in a
period D.sub.CP along the time axis in the horizontal direction.
The period D.sub.CP may be defined in units of subframes, radio
frames, milliseconds, seconds, or the like, for example.
[0072] At time T.sub.0, X.sub.0 secondary systems are activated.
The transmit power to be allocated to the X.sub.0 secondary systems
is calculated over a time duration Do. Since the time duration Do
is shorter than the period D.sub.CP, each secondary system is
notified of the power allocation result in a timely manner. At time
T.sub.1(=T.sub.0+D.sub.CP), X.sub.1 secondary systems are
additionally activated. The transmit power to be allocated to the
X.sub.0+X.sub.1 secondary systems is calculated over a time
duration D.sub.1. Since the time duration D.sub.1 is shorter than
the period D.sub.CP, each secondary system is notified of the power
allocation result in a timely manner. At time T.sub.2, X.sub.2
secondary systems are additionally activated. The transmit power to
be allocated to the X.sub.0+X.sub.1+X.sub.2 secondary systems is
calculated over a time duration D.sub.2. Since the time duration
D.sub.2 is longer than the period D.sub.CP, the notification to
each secondary system of the power allocation result is delayed
until after the next calculation period starts at time T.sub.3. At
time T.sub.3, X.sub.3 secondary systems are additionally activated.
The transmit power to be allocated to the
X.sub.0+X.sub.1+X.sub.2+X.sub.3 secondary systems is calculated
over a time duration D.sub.3. The notification to each secondary
system of the power allocation result is delayed even further than
the previous time. At time T.sub.4, X.sub.0 secondary systems are
deactivated. The transmit power to be allocated to the
X.sub.1+X.sub.2+X.sub.2+X.sub.3 secondary systems is calculated
over a time duration D.sub.4. Even though the time duration D.sub.4
is shorter than the period D.sub.CP, the effects of the delay from
the previous time still remain, and thus the notification to each
secondary system of the power allocation result is delayed until
after the next calculation period starts at time T.sub.5.
[0073] Such delay may lead various adverse effects, such as a loss
of communication opportunities for the secondary systems because
transmit power is not allocated, a drop in resource utilization
efficiency, and the production of harmful interference caused by
the power allocation not being updated in a timely manner.
Accordingly, in the embodiment discussed later, to counteract these
adverse effects and achieve both prevention of harmful interference
and promptness of power allocation, there is realized a mechanism
that adaptively switches the algorithm for power allocation between
an existing technique having a large calculation cost, and a
simpler technique of estimating the margin. The existing technique
having a large calculation cost may be the power distribution
method described in Patent Literature 1 or the margin minimization
method described in Non-Patent Literature 2, for example.
2. Examples of Power Calculation Model
2-1. Existing Technique
[0074] Herein, a power calculation model that resembles the model
described in Non-Patent Literature 2 will be described briefly.
[0075] In this power calculation model, the transmit power to
allocate to each secondary system is calculated by using a nominal
transmit power of the relevant secondary system and a margin for
interference avoidance. The nominal transmit power
P.sub.IB.sup.SingleWSD of a secondary system may also be called the
maximum radiated power, and be calculated according to the
following formula. The reference point in this case is the closest
location on the protection contour from the master device (or the
position of the closest primary transceiver). When a primary
transceiver is not present, the reference point may also be set to
infinity. Note that in this specification, formulas are expressed
in decibel form as a general rule.
[Math. 1]
P.sub.IB.sup.SingleWSD.ltoreq.m.sub.Z-m.sub.G-r(df)-SM (1)
[0076] In Expression (1), m.sub.Z is the minimum receiving
sensitivity of a primary terminal, m.sub.G is the path gain, r(df)
is the protection ratio corresponding to a discrete frequency df,
and SM is the shadowing margin. The path gain may depend on the
distance between the location where the device is present and the
reference point, and the antenna height of the device. The
protection ratio may depend on the frequency channel to be
secondarily used. The transmit power P.sub.IB.sup.WSD to allocate
to each secondary system is calculated by subtracting the
interference avoidance margin IM from the nominal transmit power
according to the following expression, so that the level of
aggregated interference from multiple secondary systems does not
become harmful at the reference point.
[Math. 2]
P.sub.IB.sup.WSD.ltoreq.P.sub.IB.sup.SingleWSD-IM (2)
[0077] Whereas the nominal transmit power P.sub.IB.sup.SingleWSD is
different for each secondary system, in principle the interference
avoidance margin IM may be shared in common for all secondary
systems. To calculate the interference avoidance margin IM, the
three techniques of the fixed margin method, the flexible margin
method, and the margin minimization method are known.
[0078] In the fixed margin method, the interference avoidance
margin IM is calculated according to the following expression using
the total number N.sub.Potential of secondary systems.
[Math. 3]
IM=10 log.sub.10(N.sub.potential) (3)
[0079] In the flexible margin method, the interference avoidance
margin IM is calculated according to the following expression using
the number N.sub.Active(f.sub.WSD) of active secondary system per
channel. Note that herein, an active secondary system may mean
simply an activated system, or mean a system using a transmit power
exceeding some base value in the channel f.sub.WSD.
[ Math . 4 ] IM = 10 log 10 ( max f ( N Active ( f WSD ) ) ) ( 4 )
##EQU00001##
[0080] In the margin minimization method, the interference
avoidance margin IM is calculated according to the following
expression using the total number N.sub.Potential of secondary
systems and a margin reduction term a.
[Math. 5]
IM=10 log.sub.10(N.sub.Potential)-.alpha. (5)
[0081] where .alpha.=m.sub.Z-r(0)-SM-I.sub.Agg,max
[0082] Herein, r(0) represents the protection ratio of a discrete
frequency zero, or in other words a co-channel, while I.sub.Agg,max
represents the aggregated interference quantity at the reference
point where interference is greatest. This aggregated interference
quantity may also include interference quantities from other
systems. In the fixed margin method and the flexible margin method,
the primary system is carefully protected, but in the margin
minimization method, the throughput of the secondary system is
raised by the contribution of the margin reduction term a, and the
resource utilization efficiency may be improved. However, in the
margin minimization method, deriving the aggregated interference
quantity I.sub.Agg,max demands evaluation of the levels of
aggregated interference at all reference points.
2-2. Simpler Technique
(1) Relationship Between Number of Secondary Systems and Margin
Adjustment
[0083] According to an embodiment, when the number of secondary
systems changes after transmit power is allocated to the secondary
systems according to the power calculation model discussed above,
the previously calculated transmit power may be adjusted on the
basis of the variation in the number of secondary systems. The
adjustment of transmit power is conducted simply by adjusting the
interference avoidance margin IM on the basis of the variation in
the number of secondary systems. The following relational
expression holds true among the already-allocated interference
avoidance margin that was calculated at a previous base point in
time (according to the margin minimization method, for example),
the adjusted interference avoidance margin IM, and the margin
adjustment.
[Math. 6]
IM'=IM.sub.Base+dM (6)
[0084] Herein, IM' is the adjusted interference avoidance margin,
IM.sub.Base is the interference avoidance margin at the base point
in time (the base value of adjustment), and dM is the margin
adjustment.
[0085] At this point, provided that N.sub.WSD is the number of
secondary systems at the base point in time, and N.sub.WSD_VAR is
the variation in the number of secondary systems since the base
point in time, the margin adjustment dM may be expressed as follows
from Expressions (5) and (6). Note that the number of secondary
systems and the variation thereof may refer to active devices only,
or to the total number.
[Math. 7]
dM = IM ' - IM Base = 10 log 10 ( N WSD + N WSD _ VAR ) - .alpha.
Adj - ( 10 log 10 ( N WSD ) - .alpha. Prev ) = 10 log 10 ( N WSD +
N WSD _ VAR N WSD ) - .alpha. Adj + .alpha. Prev = 10 log 10 ( N
WSD + N WSD _ VAR N WSD ) + 10 log 10 ( Y + sgn ( N WDS _ VAR ) 10
dI 10 ) - 10 log 10 ( Y ) = 10 log 10 ( N WSD + N WSD _ VAR N WSD Y
+ sgn ( N WDS _ VAR ) 10 dI 10 Y ) where sgn ( x ) = { 1 : x > 0
0 : x = 0 - 1 : x < 0 and Y = 10 I Agg , max 10 ( 7 )
##EQU00002##
[0086] In Expression (7), dI represents the magnitude of the
variation in the aggregated interference quantity I.sub.Agg,max
corresponding to the variation N.sub.WSD_VAR in the number of
secondary systems (hereinafter called the estimated interference
variation). To reduce the calculation cost, the estimated
interference variation dI is not calculated precisely, but instead
estimated simply on the basis of the variation N.sub.WSD_VAR in the
number of secondary systems. Several techniques for calculating the
estimated interference variation dI are described below.
(2-1) Calculation of Estimated Interference Variation (First
Technique)
[0087] In the first technique, the estimated interference variation
dI is estimated using a table that defines a mapping between the
variation N.sub.WSD_VAR in the number of secondary systems and the
estimated interference variation dI. Table 1 and Table 2
respectively illustrate examples of mapping tables. In Table 1, the
estimated interference variation dI is mapped directly to the
variation N.sub.WSD_VAR in the number of secondary systems. On the
other hand, in Table 2, the estimated interference variation dI is
mapped to a range to which the variation N.sub.WSD_VAR in the
number of secondary systems belongs.
TABLE-US-00001 TABLE 1 Example of mapping between variation
N.sub.WSD_VAR in number of secondary systems and estimated
interference variation dI N.sub.WSD_VAR dI (dB) K.sub.1 dI.sub.1
K.sub.2 dI.sub.2 K.sub.3 dI.sub.3 . . . . . . K.sub.x dI.sub.X
TABLE-US-00002 TABLE 2 Another example of mapping between variation
N.sub.WSD_VAR in number of secondary systems and estimated
interference variation dI Range of N.sub.WSD_VAR dI (dB) [K.sub.1,
K.sub.2] dI.sub.1 [K.sub.2, K.sub.3] dI.sub.2 [K.sub.3, K.sub.4]
dI.sub.3 . . . . . . [K.sub.X-1, K.sub.X] dI.sub.X
[0088] According to the first technique, by performing a lookup in
a predefined mapping table, the estimated interference variation dI
may be derived with a small calculation cost.
(2-2) Calculation of Estimated Interference Variation (Second
Technique)
[0089] In the second technique, the estimated interference
variation dI is estimated on the basis of an assumption that the
number of secondary systems and the aggregated interference
quantity are proportional. Under this assumption, the estimated
interference variation dI may be expressed as in the following
expression.
[ Math . 8 ] dI = 10 log 10 ( N WSD _ VAR N WSD Y ) ( 8 )
##EQU00003##
[0090] Substituting Expression (8) into Expression (7), the
relational expression between the number of secondary systems and
the margin adjustment may be transformed as follows.
[ Math . 9 ] dM = 10 log 10 ( N WSD + N WSD _ VAR N WSD Y + sgn ( N
WDS _ VAR ) ( N WSD _ VAR N WSD Y ) Y ) = 10 log 10 ( N WSD + N WSD
_ VAR N WSD ( 1 + N WSD _ VAR N WSD ) ) = 20 log 10 ( 1 + N WSD _
VAR N WSD ) ( 9 ) ##EQU00004##
[0091] Consequently, in this case, the margin adjustment dM may be
computed simply, using only the number N.sub.WSD of secondary
systems at the base point in time and the variation N.sub.WSD_VAR
in the number of secondary systems.
[0092] Note that by incorporating the approach of the flexible
margin method into Expression (7), the margin adjustment dM may
also be computed as in the following expression.
[ Math . 10 ] dM = 10 log 10 ( ( 1 + N WSD _ VAR N WSD max m ( f m
( N WSD _ VAR ) ) N channel ) N WSD + N WSD _ VAR N WSD ) ( 10 )
##EQU00005##
[0093] In Expression (10), f.sub.m(N.sub.WSD_VAR) expresses the
number of secondary systems to which the mth frequency channel is
allocated from among the variation N.sub.WSD_VAR in the number of
secondary systems.
(2-3) Calculation of Estimated Interference Variation (Third
Technique)
[0094] In the third technique, the estimated interference variation
dI is estimated according to the following expression as a worst
case.
[ Math . 11 ] dI = 10 log 10 ( 10 I TH 10 - 10 I Agg , max 10 ) (
11 ) ##EQU00006##
[0095] In Expression (11), I.sub.TH represents a threshold value
that may correspond to the maximum value of the aggregated
interference allowed by the primary terminal.
(3) Technique for Counting Number of Secondary Systems
[0096] The number of secondary systems in the power calculation
model described in this section may be based on one or both of the
number of master devices and the number of slave devices in the
secondary systems. For example, when the secondary systems are
operated and managed according to a time-division scheme, and the
slave devices use a transmit power approximately equal to (or lower
than) the transmit power of the master device, it is sufficient to
count only the number of master devices as the number of secondary
systems. On the other hand, when a master device and a slave device
potentially may transmit signals at the same time, for example, the
calculation of a safe power may be ensured by counting both master
devices and slave devices as the number of secondary systems.
[0097] These numbers of devices may also be calculated by including
weights depending on the device configuration. As used herein, the
device configuration may include one or more from among the antenna
height, the transmit power (which may be a maximum or desired
transmit power, or the allocated transmit power for an existing
device), and the frequency channel to be used. As an example, the
higher the antenna of a device, the greater is the contribution to
interference of a signal emitted from that device. Accordingly, by
counting (performing a weighted sum of) the number of devices using
ratios of antenna heights among the devices as weights, the risk of
harmful interference may be effectively reduced through power
recalculation or adjustment.
[0098] A mechanism that allocates transmit power to secondary
systems in a timely manner using the power calculation model
described in this section will now be described in the subsequent
sections.
3. Exemplary Configuration of Communication Control Apparatus
3-1. Component Configuration
[0099] FIG. 6 is a block diagram illustrating an example of a
logical configuration of the communication control apparatus 100
according to an embodiment. Referring to FIG. 6, the communication
control apparatus 100 includes a communication unit 110, a storage
unit 120, and a control unit 130.
(1) Communication Unit
[0100] The communication unit 110 communicates with the wireless
communication apparatus 20 via backhauling of the wireless
communication apparatus 20. For example, the communication unit 110
receives an activation request from a wireless communication
apparatus 20 that has been activated or moved to the geographical
region managed by the communication control apparatus 100. The
communication unit 110 also receives secondary system information
to be discussed later from the relevant wireless communication
apparatus 20. Subsequently, after a calculation for the purpose of
power allocation is executed by the control unit 130, the
communication unit 110 transmits power allocation-related
information based on the calculation result to the wireless
communication apparatus 20.
[0101] The communication unit 110 may also communicate with the
primary transceiver 10 and the control nodes on the core network
15. Additionally, the communication unit 110 may also communicate
with a data server (for example, a GLDB that manages a neighboring
region) having the authority to allocate transmit power in a region
near the geographical region managed by the communication control
apparatus 100.
(2) Storage Unit
[0102] The storage unit 120 uses a storage medium such as a hard
disk or semiconductor memory to store programs and data for the
operation of the communication control apparatus 100. Data stored
by the storage unit 120 includes, for example, primary system
information collected from the primary transceiver 10 or control
nodes on the core network 15, or stored in advance. The primary
system information may include one or more from among the position
of the primary transceiver, the service area deployment, protected
frequency channels, the minimum receiving sensitivity of the
primary terminals, the protection ratio, the shadowing margin, the
allowed interference level, an identifier of a wireless access
technology, and a measured interference level, for example. The
position of the primary transceiver and the service area deployment
may be used when specifying a reference point in the power
calculation model discussed earlier, for example.
[0103] In addition, the data stored by the storage unit 120
includes secondary system information collected from each of the
wireless communication apparatuses 20. The secondary system
information may include one or more from among the identifier of
the master device, the position, the antenna height, the device
type, emission characteristics (for example, the adjacent channel
leakage ratio (ACLR)), an identifier of a wireless access
technology, and transmit power information (for example, maximum
transmit power and/or desired transmit power).
[0104] In addition, the data stored by the storage unit 120 may
include power allocation-related information reported to the
wireless communication apparatus 20. The power allocation-related
information may include one or more from among a list of frequency
channels available for use, a nominal transmit power (maximum
radiated power), an interference avoidance margin, an adjustment of
the interference avoidance margin, and the period of validity for
the information.
[0105] In addition, the data stored by the storage unit 120
includes parameters used to calculate the power allocation. The
parameters herein may include one or more from among a power
allocation calculation period, a determination threshold to be
compared against the number of secondary systems, a mapping table
for deriving the estimated interference variation, as well as the
number of secondary systems, the aggregated interference quantity,
and the interference avoidance margin at a previous base point in
time, for example.
(3) Control Unit
[0106] The control unit 130 controls overall operation of the
communication control apparatus 100. In the present embodiment, the
control unit 130 includes a determination unit 132, a calculation
unit 134, and a signaling unit 136.
(3-1) Determination Unit
[0107] When there is a change in the number of secondary systems
within the geographic region managed by the communication control
apparatus 100, the determination unit 132 switches the calculation
process for the purpose of power allocation to be executed by the
calculation unit 134, according to a condition depending on the
number of secondary systems. As an example, when the changed number
of secondary systems falls below a determination threshold, the
determination unit 132 causes the calculation unit 134 to
recalculate the transmit power that should be allocated to the
secondary systems according to the margin minimization method in
the power calculation model discussed earlier. Also, when the
changed number of secondary systems exceeds a determination
threshold, the determination unit 132 causes the calculation unit
134 to adjust the previously calculated transmit power. The
determination threshold herein is configured so that the estimated
calculation time dependent on the number of secondary systems does
not exceed an allowed calculation time.
[0108] The allowed calculation time may be configured in advance
according to any conditions, such as the requirements for the
operation and management of the secondary systems, the hardware
limitations of the communication control apparatus 100, and the
rules of the carrier that operates and manages the communication
control apparatus 100. In addition, the determination unit 132 may
also configure the allowed calculation time dynamically in response
to a processing condition such as the load imposed on the
processing resources (such as a processor and memory) of the
communication control apparatus 100 or the number of processor
cores available for use. The allowed calculation time may also be
equal to the power allocation calculation period discussed earlier.
As an example, in the standard specification of the LTE scheme
specified by the 3GPP, the scheduling period in an eNodeB is
implementation-dependent, and may be configured to various values,
such as one subframe (=1 ms) or one radio frame (=10 ms). The
allowed calculation time may also be equal to such a scheduling
period.
[0109] For example, the determination unit 132 tracks changes in
the number of secondary systems by monitoring activation requests
and deactivation requests received from the wireless communication
apparatus 20. N.sub.WSD represents the number of secondary systems
at a base point in time, while N.sub.WSD_VAR represents the
variation in the number of secondary systems since the base point
in time. The determination condition for switching the calculation
process in the calculation unit 134 may then be expressed as
follows.
[Math. 12]
N.sub.WSD+N.sub.WSD_VAR>N.sub.TH (12)
[0110] When the conditional Expression (12) is satisfied, the
determination unit 132 causes the calculation unit 134 to adjust
the previously calculated transmit power on the basis of the
variation N.sub.WSD_VAR in the number of secondary systems.
[0111] In the margin minimization method discussed earlier,
provided that N.sub.Channel is the number of frequency channels
protected for the primary system, the number N.sub.Calc of
individual interference quantity calculations executed when
calculating the aggregated interference for all reference points is
expressed by the following expression.
[Math. 13]
N.sub.Calc=N.sub.ChannelN.sub.WSD.sup.2 (13)
[0112] Furthermore, provided that f.sub.clock is the clock
frequency of the processor, N.sub.CalcPerClock is the number of
interference quantities that may be calculated in one clock cycle,
and D.sub.TH is the allowed calculation time, the maximum number of
interference quantities that may be calculated in the calculation
time D.sub.TH is equal to the product of D.sub.TH, f.sub.clock, and
N.sub.CalcPerClock. Consequently, the determination threshold
N.sub.TH in the conditional Expression (12) may be derived as
follows.
[ Math . 14 ] N TH = D TH f Clock N CalcPerClock N Channel ( 14 )
##EQU00007##
[0113] Note that Expression (14) is merely one example. For
example, a margin may also be included in the determination
threshold N.sub.TH.
[0114] In a practical example, the base point in time may be the
time when the transmit power was recalculated last by the
calculation unit 134. In this practical example, provided that the
transmit power was recalculated last at time T.sub.1, for example,
the determination unit 132 retains the number of secondary systems
at time T.sub.1 as a base value N.sub.WSD with a variation of zero,
even if the transmit power is later adjusted at time T.sub.2. In
this case, even if the transmit power is roughly adjusted several
times with the simple technique, adjustment error does not
accumulate, and the risk of producing harmful interference caused
by error accumulation is avoided.
[0115] In another practical example, the base point in time may be
the immediately previous time when the transmit power was
recalculated or adjusted. In this practical example, if the
transmit power is adjusted at time T.sub.2, the determination unit
132 retains the number of secondary systems at time T.sub.2 as the
base value N.sub.WSD with a variation of zero. In this case, since
it is sufficient for the determination unit 132 to retain only the
number of secondary systems from the most recent and immediately
previous calculation period, the implementation of the calculation
process may be simplified.
[0116] Note that the technique of simply adjusting only the
interference avoidance margin on the basis of the variation in the
number of secondary systems enables a result to be obtained with a
small calculation cost, while sacrificing a degree of power
allocation optimization. However, there exist other factors causing
the risks of interference to vary besides variation in the number
of secondary systems. Accordingly, the determination unit 132
additionally may determine whether to cause the calculation unit
134 to recalculate the transmit power or adjust the previously
calculated transmit power, according to an additional determination
condition that depends on factors other than the variation in the
number of secondary systems. Herein, the factors governing the
additional determination condition may be at least one from among
the reference point, the frequency channel to be secondarily used,
the antenna height of the device, and the interference level from
other systems, for example. For example, when the degree of
variation for these factors is large, the additional determination
condition may be determined to be satisfied, and the interference
avoidance margin may be adjusted.
(3-2) Calculation Unit
[0117] The calculation unit 134 calculates the transmit power that
should be allocated to one or more secondary systems that
secondarily use frequency channels protected for the primary
system. In the present embodiment, as long as the above
determination condition for switching the calculation process is
not satisfied, the calculation unit 134 recalculates (calculates)
the transmit power to be allocated to each secondary system
according to the margin minimization method discussed earlier, for
example. In this case, the transmit power of each secondary system
may be calculated by using the nominal transmit power
P.sub.IB.sup.SingleWSD and the interference avoidance margin IM, as
indicated in Expression (2).
[0118] When the above determination condition is satisfied, the
calculation unit 134 adjusts the interference avoidance margin IM
by calculating only the margin adjustment dM on the basis of the
variation N.sub.WSD_VAR in the number of secondary systems, as
illustrated in Expression (7) or Expression (9). The calculation
unit 134 may calculate the margin adjustment dM by substituting
into Expression (7) the variation N.sub.WSD_VAR in the number of
secondary systems, the variation dI in the interference quantity
estimated on the basis of N.sub.WSD_VAR, and the aggregated
interference quantity I.sub.Agg,max at the base point in time, for
example. At this point, the calculation unit 134 may also derive
the estimated interference variation dI using a mapping table that
defines a mapping between the variation N.sub.WSD_VAR in the number
of secondary systems and the estimated interference variation dI.
Also, the calculation unit 134 may calculate the margin adjustment
dM by substituting the number N.sub.WSD of secondary systems and
the variation N.sub.WSD_VAR thereof into Expression (9) based on
the assumption that the number of secondary systems and the
aggregated interference quantity are proportional, for example. In
either case, calculation costs that increase on the order of the
square of the number of secondary systems are not required.
Compared to a technique that recalculates the transmit power for
the system as a whole, the calculation of the adjustment dM of the
interference avoidance margin is completed within a shorter amount
of time.
[0119] When the number of secondary systems increases, or in other
words when an active wireless communication apparatus 20 newly
occurs, the calculation unit 134 may calculate the nominal transmit
power of the secondary system operated and managed by the new
wireless communication apparatus 20. The nominal transmit power
P.sub.IB.sup.SingleWSD is calculated using parameters included in
the primary system information and the secondary system
information, in accordance with Expression (1). Depending on the
load on the calculation unit 134, the calculation of the nominal
transmit power may also be entrusted to the secondary systems. For
example, when the load on the calculation unit 134 is higher than a
designated threshold in a certain calculation period, the
calculation unit 134 may entrust the calculation of the nominal
transmit power to the secondary systems. In this case, parameters
for calculating the nominal transmit power may be signaled to the
wireless communication apparatus 20 that is the master device of a
relevant secondary system.
(3-3) Signaling Unit
[0120] The signaling unit 136 executes signaling via the
communication unit 110 with the primary transceiver 10, control
nodes on the core network 15, the wireless communication apparatus
20, and other data servers. For example, every time the calculation
unit 134 recalculates the transmit power to allocate to each
secondary system or adjusts the interference avoidance margin,
power allocation-related information is reported to the wireless
communication apparatus 20 that is the master device of an active
secondary system.
[0121] As an example, according to Expression (2), the transmit
power P.sub.IB.sup.WSD allocated to each secondary system includes
the nominal transmit power P.sub.IB.sup.SingleWSD and the
interference avoidance margin IM. Whereas the nominal transmit
power P.sub.IB.sup.SingleWSD is different for each system, the
interference avoidance margin IM is shared in common for multiple
secondary systems. In the calculation period in which the
interference avoidance margin IM is adjusted, or in other words, in
the calculation period in which the changed number of secondary
systems satisfies the conditional Expression (12), the nominal
transmit power P.sub.IB.sup.SingleWSD is not updated, and only the
margin adjustment dM indicated in Expression (6) is calculated. In
this case, the signaling unit 136 signals only the adjustment dM of
the interference avoidance margin calculated by the calculation
unit 134 to existing secondary systems. Consequently, the signaling
overhead is reduced. To the new secondary systems, the signaling
unit 136 signals the adjustment dM of the interference avoidance
margin, as well as the interference avoidance margin IM.sub.Base
and the nominal transmit power P.sub.IB.sup.SingleWSD that were
reported to the existing secondary systems at the previous base
point in time. The wireless communication apparatus 20 which is the
master device of a secondary system derives the adjusted
interference avoidance margin IM' by adding together the
interference avoidance margin IM.sub.Base from the base point in
time and the margin adjustment dM. Note that the signaling unit 136
may also signal the adjusted interference avoidance margin IM' to
both the existing secondary systems and the new secondary systems.
Additionally, the signaling unit 136 may also signal the allocated
transmit power P.sub.IB.sup.WSD to the secondary systems at some
timing.
[0122] When the calculation of the nominal transmit power is
entrusted to the secondary system according to the load on the
calculation unit 134, the signaling unit 136 signals parameters for
calculating the nominal transmit power to the new secondary
systems. The parameters for calculating the nominal transmit power
may include one or more from among the position of the primary
transceiver, the list of frequency channels available for use, the
minimum receiving sensitivity of the primary terminals, the
protection ratio, the shadowing margin, and the total number of
secondary systems (N.sub.WSD+N.sub.WSD_VAR), for example. In this
case, the transmit power is calculated by the wireless
communication apparatus 20 itself which is the master device of a
new secondary system. The signaling unit 136 may also receive a
report of the nominal transmit power calculation result from the
wireless communication apparatus 20, and store the report in the
storage unit 120.
[0123] In the calculation period in which the transmit power is
recalculated, or in other words, in the calculation period in which
the changed number of secondary systems does not satisfy the
conditional Expression (12), the nominal transmit power
P.sub.IB.sup.SingleWSD possibly may be updated. Additionally, the
interference avoidance margin IM is also recalculated. The
signaling unit 136 signals the recalculated nominal transmit power
P.sub.IB.sup.SingleWSD and the interference avoidance margin IM to
the existing secondary systems and the new secondary systems. The
interference avoidance margin IM reported at this point may be
treated as a base value for later adjustment of the interference
avoidance margin. For existing secondary systems, the signaling of
the nominal transmit power to the existing secondary systems may
also be omitted when the nominal transmit power is not updated.
Additionally, the signaling to the existing secondary systems may
also be conducted by transmitting a difference only.
[0124] A signaling message by which the signaling unit 136 reports
power allocation-related information to the wireless communication
apparatus 20 may also include an index indicating the type of
parameters being reported. For example, parameter types may be
defined as follows.
[0125] 0: Interference avoidance margin (IM) *may also be used as
base value IM.sub.Base
[0126] 1: Margin adjustment (dM)
[0127] 2: Interference avoidance margin and margin adjustment (IM,
dM)
[0128] 3: Adjusted margin (IM'=IM.sub.Base+dM)
[0129] 4: Allocated transmit power
The values of the parameter types are not limited to the above
example, and may also be other values. By introducing such an index
into the signaling message, it becomes possible for the
communication control system 1 to support a variety of signaling
variations, and select an optimal signaling method from the
perspective of reducing overhead, reducing the complexity of the
implementation, or the like.
[0130] As described using FIG. 3, the communication control
apparatus 100 may also be a data server having the authority to
allocate transmit power to one or more secondary systems inside a
geographical region 3a, for example. However, when allocating
transmit power, situations demanding the consideration of the
presence of secondary systems inside a neighboring region 3b that
neighbors the geographical region 3a may also exist. An example of
such a situation is when a large number of secondary systems or a
secondary system that uses a comparatively large transmit power is
operated near the region border. In this case, the signaling unit
136 may acquire information indicating the number of secondary
systems that should be considered inside the neighboring region 3b
from another data server having the authority to allocate transmit
power to secondary systems for the neighboring region 3b. At this
point, suppose that N.sub.WSD_A is the number of secondary systems
inside the geographical region 3a, and N.sub.WSD_B is the number of
secondary systems that should be considered, which is acquired from
another data server. When these values satisfy the following
conditional Express (15), the assumed calculation time for
recalculating the transmit power by the calculation unit 134 will
exceed the allowed calculation time.
[Math. 15]
N.sub.WSD_A+N.sub.WSD_B>N.sub.TH (15)
[0131] A comparison of the condition Expression (12) and the
conditional Expression (15) shows that the number of secondary
systems N.sub.WSD_A means the base value N.sub.WSD of the number of
secondary systems, while the number of secondary systems
N.sub.WSD_B means the variation N.sub.WSD_VAR in secondary systems
in the spatial direction. When the determination condition of the
conditional Expression (15) is satisfied, the determination unit
132 causes the calculation unit 132 to adjust the interference
avoidance margin IM included in the transmit power previously
calculated by considering only the geographical region 3a on the
basis of the variation N.sub.WSD_B in the number of secondary
systems. Since the number of secondary systems N.sub.WSD_B is
positive, Expression (7) may be transformed as follows.
[ Math . 16 ] dM = 10 log 10 ( N WSD _ A + N WSD _ B N WSD _ A Y +
10 dI 10 Y ) where Y = 10 I Agg , max 10 ( 16 ) ##EQU00008##
[0132] In this way, according to the present embodiment, even in a
situation demanding the consideration of the presence of secondary
systems inside a neighboring region, it is sufficient for the
communication control apparatus 100 simply to acquire only the
number of secondary systems that should be considered from a device
having authority for the relevant neighboring region. The
communication control apparatus 100, by adjusting the interference
avoidance margin using the acquired number of secondary systems, is
able to give communication opportunities to secondary systems
promptly, while also appropriately protecting the primary system.
Note that the signaling unit 136 may also acquire other parameters,
such as the estimated interference variation dI, from the device
having authority for the neighboring region.
3-2. Modifications
[0133] When the variation N.sub.WSD_VAR in the number of secondary
systems is small, the margin adjustment dM is also small. In such
cases, if the margin adjustment dM is signaled every time the
number of secondary systems changes, the signaling overhead in the
communication control system 1 becomes very large, possibly causing
a drop in resource utilization efficiency. Accordingly, this
section describes techniques for reducing the overhead of power
allocation signaling as modifications of the embodiment discussed
above.
(1) First Modification
[0134] In the first modification, the margin for reducing signaling
overhead proposed in Patent Literature 2 is introduced. The
calculation unit 134 calculates a transmit power
P.sub.Alloc.sup.WSD to be allocated to each secondary system by
using a signaling reduction margin M.sub.int in addition to the
nominal transmit power P.sub.IB.sup.SingleWSD and the interference
avoidance margin IM, as in the following expression.
[Math. 17]
P.sub.Alloc.sup.WSD=P.sub.IB.sup.WSD-M.sub.Int.ltoreq.P.sub.IB.sup.Singl-
eWSD-IM-M.sub.Int (17)
[0135] When the number of secondary systems increases, if the total
number of secondary systems exceeds the determination threshold Nm,
the calculation unit 134 calculates the adjustment dM of the
interference avoidance margin IM in Expression (17) on the basis of
the variation N.sub.WSD_VAR in the number of secondary systems. At
this point, when the following conditional Expression (18) is
satisfied, harmful interference does not occur, even if the
secondary systems continually use the already-allocated transmit
power P.sub.Alloc.sup.WSD. Note that the right side of the
conditional Expression (18) is equal to the already-allocated
transmit power P.sub.Alloc.sup.WSD.
[Math. 18]
P.sub.IB.sup.SingleWSD-(IM+dM).gtoreq.P.sub.IB.sup.SingleWSD-IM-M.sub.In-
t (18)
[0136] The condition Expression (18) may be transformed
equivalently as follows.
[Math. 19]
IM+dM.ltoreq.IM+M.sub.Int
dM.ltoreq.M.sub.Int (19)
[0137] Accordingly, when the adjustment dM of the interference
avoidance margin for existing secondary systems falls below the
signaling reduction margin M.sub.Int included in the
already-allocated transmit power, the signaling unit 136 does not
signal the margin adjustment dM to the relevant existing secondary
systems.
[0138] Likewise, when the number of secondary systems decreases, if
the total number of secondary systems exceeds the determination
threshold N.sub.TH, the calculation unit 134 calculates the
adjustment dM of the interference avoidance margin IM in Expression
(17) on the basis of the variation N.sub.WSD_VAR in the number of
secondary systems. At this point, when the following conditional
Expression (20) is satisfied, the throughput improvement obtained
by adjusting the transmit power of the secondary systems is
small.
[Math. 20]
|dM|.ltoreq.M.sub.TH_Int (20)
[0139] Herein, M.sub.TH_Int is a threshold for reducing signaling
overhead that may be configured in advance. When the absolute value
of the adjustment dM of the interference avoidance margin for
existing secondary systems falls below the threshold M.sub.TH_Int
for reducing signaling overhead, the signaling unit 136 does not
signal the margin adjustment dM to the relevant existing secondary
systems.
(2) Second Modification
[0140] In the second modification, instead of performing strict
tracking of the number of secondary systems, a type of hysteresis
control is introduced to thereby reduce the number of times power
allocation is calculated. When adjusting the transmit power, the
calculation unit 134 calculates the margin adjustment dM by setting
the variation N.sub.WSD_VAR in the number of secondary systems to a
greater-than-actual virtual value N.sub.WSD_VAR, as in the
following expression.
[ Math . 21 ] dM = 10 log 10 ( N WSD + N WSD _ VAR ' N WSD Y + sgn
( N WDS _ VAR ' ) 10 dI 10 Y ) ( 21 ) ##EQU00009##
[0141] After that, even if the number of secondary systems
increases, as long as the total number of secondary systems
(N.sub.WSD+N.sub.WSD_VAR) does not exceed the virtual value
(N.sub.WSD+N.sub.WSD_VAR'), the calculation unit 134 does not have
to execute adjustment of the interference avoidance margin.
Consequently, signaling to each secondary system is made less
frequent. The virtual value N.sub.WSD_VAR' may be configured
statically in advance, or configured dynamically. For example, the
calculation unit 134 may retain maximum numbers of secondary
systems managed by the communication control apparatus 100 at
different times as a history of communication, and configure the
virtual value N.sub.WSD_VAR' so that the virtual number of
secondary systems (N.sub.WSD+N.sub.WSD_VAR') becomes equal to the
relevant maximum number. Consequently, since a larger interference
avoidance margin is calculated proactively before the number of
secondary systems increases, transmit power may be allocated to new
secondary systems promptly, without exerting harmful interference
on the primary system. A period of validity may also be configured
for the virtual value N.sub.WSD_VAR'. In this case, after the
period of validity has passed, the calculation unit 134 may execute
adjustment of the interference avoidance margin (or recalculation
of the transmit power) irrespectively of the virtual value
N.sub.WSD_VAR', and signal the power allocation result to the
secondary systems.
[0142] Likewise, in the case in which the number of secondary
systems decreases, as long as the absolute value |N.sub.WSD_VAR| of
the variation in the number of secondary systems does not exceed a
designated threshold, the calculation unit 134 does not have to
execute adjustment of the interference avoidance margin.
4. Process Flows
[0143] In this section, several examples of the flows of processes
that may be executed by the communication control apparatus 100
according to the foregoing embodiment will be described.
4-1. Power Distribution Process
(1) First Example
[0144] FIG. 7A is a flowchart illustrating a first example of the
flow of a power distribution process according to an embodiment. In
the first example, the time at which the transmit power was
recalculated last by the calculation unit 134 is treated as the
base point in time for the variation in the number of secondary
systems.
[0145] Referring to FIG. 7A, first, the determination unit 132
stands by a change in the number of secondary systems (step S110).
Subsequently, when the number of secondary systems changes, the
process proceeds to step S115.
[0146] Next, the determination unit 132 determines whether the
changed number of secondary systems (N.sub.WSD+N.sub.WSD_VAR)
exceeds the determination threshold N.sub.TH (step S115). If the
changed number of secondary systems does not exceed the
determination threshold, the process proceeds to step S120. On the
other hand, if the changed number of secondary systems exceeds the
determination threshold, the process proceeds to step S140.
[0147] In step S120, the calculation unit 134 recalculates the
nominal transmit power and the interference avoidance margin
according to the power distribution method described in Patent
Literature 1 or the margin minimization method described in
Non-Patent Literature 2 (step S120). Subsequently, the signaling
unit 136 reports the recalculated nominal transmit power and
interference avoidance margin to the wireless communication
apparatus 20 which is the master device of each of the existing
secondary systems and the new secondary systems (step S125). Also,
the calculation unit 134 updates the base value N.sub.WSD of the
number of secondary systems and the maximum aggregated interference
quantity I.sub.Agg,max at the base point in time to the most recent
values (step S130).
[0148] In step S140, the calculation unit 134 adjusts the
interference avoidance margin IM by calculating the adjustment dM
of the interference avoidance margin on the basis of the variation
N.sub.WSD_VAR in the number of secondary systems (step S140).
Subsequently, the signaling unit 136 reports the margin adjustment
dM calculated by the calculation unit 134 to the wireless
communication apparatus 20 which is the master device of each of
the existing secondary systems (step S145).
[0149] Furthermore, the calculation unit 134 determines whether to
calculate the nominal transmit power for the new secondary systems,
depending on the load at the time (step S150). For example, when
the load on the calculation unit 134 is relatively high, the
calculation of the nominal transmit power is entrusted to the
secondary systems. In this case, the signaling unit 136 reports
parameters for calculating the nominal transmit power, the
interference avoidance margin and the adjustment thereof to the
wireless communication apparatus 20 which is the master device of
each of the new secondary systems (step S155). On the other hand,
when the load on the calculation unit 134 is relatively low, the
calculation of the nominal transmit power is not entrusted to the
secondary systems. In this case, the calculation unit 134
calculates the nominal transmit power for the new secondary systems
(step S160). Subsequently, the signaling unit 136 reports the
nominal transmit power, the interference avoidance margin and the
adjustment thereof to the wireless communication apparatus 20 which
is the master device of each of the new secondary systems (step
S165).
[0150] After that, during the period until the next calculation
timing arrives, variation in the number of secondary systems is
monitored by the determination unit 132, and the process returns to
step S110 (step S180).
(2) Second Example
[0151] FIG. 7B is a flowchart illustrating a second example of the
flow of a power distribution process according to an embodiment. In
the second example, the immediately previous time at which the
transmit power was recalculated or adjusted is treated as the base
point in time for the variation in the number of secondary systems.
Also, the determination threshold N.sub.TH is configured
dynamically. Note that the configuration is not limited to such an
example, and the determination threshold N.sub.TH may be configured
dynamically in the first example, or the determination threshold
N.sub.TH may be configured statically in advance in the second
example.
[0152] Referring to FIG. 7B, first, the determination unit 132
configures the determination threshold N.sub.TH according to a
processing condition such as the load imposed on the processing
resources of the communication control apparatus 100 or the number
of processor cores available for use (step S105). Also, the
determination unit 132 stands by for a change in the number of
secondary systems (step S110). Subsequently, when the number of
secondary systems changes, the process proceeds to step S115.
[0153] Next, the determination unit 132 determines whether the
changed number of secondary systems (N.sub.WSD+N.sub.WSD_VAR)
exceeds the determination threshold N.sub.TH (step S115). If the
changed number of secondary systems does not exceed the
determination threshold, the process proceeds to step S120. On the
other hand, if the changed number of secondary systems exceeds the
determination threshold, the process proceeds to step S140.
[0154] In step S120, the calculation unit 134 recalculates the
nominal transmit power and the interference avoidance margin
according to the power distribution method described in Patent
Literature 1 or the margin minimization method described in
Non-Patent Literature 2 (step S120). Subsequently, the signaling
unit 136 reports the recalculated nominal transmit power and
interference avoidance margin to the wireless communication
apparatus 20 which is the master device of each of the existing
secondary systems and the new secondary systems (step S125).
[0155] In step S140, the calculation unit 134 adjusts the
interference avoidance margin IM by calculating the adjustment dM
of the interference avoidance margin on the basis of the variation
N.sub.WSD_VAR in the number of secondary systems (step S140).
Subsequently, the signaling unit 136 reports the margin adjustment
dM calculated by the calculation unit 134 to the wireless
communication apparatus 20 which is the master device of each of
the existing secondary systems (step S145).
[0156] Furthermore, the calculation unit 134 determines whether to
calculate the nominal transmit power for the new secondary systems,
depending on the load at the time (step S150). For example, when
the load on the calculation unit 134 is relatively high, the
signaling unit 136 reports parameters for calculating the nominal
transmit power, the interference avoidance margin and the
adjustment thereof to the wireless communication apparatus 20 which
is the master device of each of the new secondary systems (step
S155). On the other hand, when the load on the calculation unit 134
is relatively low, the calculation unit 134 calculates the nominal
transmit power for the new secondary systems (step S160).
Subsequently, the signaling unit 136 reports the nominal transmit
power, the interference avoidance margin and the adjustment thereof
to the wireless communication apparatus 20 which is the master
device of each of the new secondary systems (step S165).
[0157] After that, the calculation unit 132 updates the base value
Nwso of the number of secondary systems and the maximum aggregated
interference quantity I.sub.Agg,max at the base point in time to
the most recent values (step S175). Subsequently, during the period
until the next calculation timing arrives, variation in the number
of secondary systems is monitored by the determination unit 132,
and the process returns to step S105 (step S180).
(3) Third Example
[0158] FIG. 7C is a flowchart illustrating a third example of the
flow of a power distribution process according to an embodiment. In
the third example, the time at which the transmit power was
recalculated last by the calculation unit 334 is treated as the
base point in time for the variation in the number of secondary
systems, similarly to the first example. In the third example, the
technique of reducing signaling overhead described as the first
modification in the previous section is introduced.
[0159] Referring to FIG. 7C, first, the determination unit 132
stands by a change in the number of secondary systems (step S110).
Subsequently, when the number of secondary systems changes, the
process proceeds to step S115.
[0160] Next, the determination unit 132 determines whether the
changed number of secondary systems exceeds the determination
threshold (step S115). If the changed number of secondary systems
does not exceed the determination threshold, the process proceeds
to step S121. On the other hand, if the changed number of secondary
systems exceeds the determination threshold, the process proceeds
to step S140.
[0161] In step S121, the calculation unit 134 recalculates the
nominal transmit power and the interference avoidance margin
according to the power distribution method described in Patent
Literature 1 or the margin minimization method described in
Non-Patent Literature 2. For recalculation, the signaling reduction
margin M.sub.Int is also introduced (step S121). Subsequently, the
signaling unit 136 reports the recalculated nominal transmit power
and margin to the wireless communication apparatus 20 which is the
master device of each of the existing secondary systems and the new
secondary systems (step S126). Also, the calculation unit 132
updates the base value N.sub.WSD of the number of secondary systems
and the maximum aggregated interference quantity I.sub.Agg,max at
the base point in time to the most recent values (step S130).
[0162] In step S140, the calculation unit 134 adjusts the
interference avoidance margin by calculating the adjustment of the
interference avoidance margin on the basis of the variation in the
number of secondary systems (step S140). Subsequently, the
signaling unit 136 determines whether the margin adjustment
calculated by the calculation unit 134 should be signaled (step
S144). For example, when the margin adjustment dM does not satisfy
the condition Expression (19) or the conditional Expression (20)
discussed earlier, the signaling unit 136 may determine that the
margin adjustment dM should be signaled. If it is determined that
the margin adjustment dM should be signaled, the signaling unit 136
reports the margin adjustment calculated by the calculation unit
134 to the wireless communication apparatus 20 which is the master
device of each of the existing secondary systems (step S145).
[0163] Furthermore, the calculation unit 134 calculates the nominal
transmit power for the new secondary systems (step S160).
Subsequently, the signaling unit 136 reports the nominal transmit
power, the interference avoidance margin, the margin adjustment,
and the signaling reduction margin to the wireless communication
apparatus 20 which is the master device of each of the new
secondary systems (step S166).
[0164] After that, during the period until the next calculation
timing arrives, variation in the number of secondary systems is
monitored by the determination unit 132, and the process returns to
step S110 (step S180).
(4) Fourth Example
[0165] FIG. 7D is a flowchart illustrating a fourth example of the
flow of a power distribution process according to an embodiment. In
the fourth example, the technique of reducing signaling overhead
described as the second modification in the previous section is
introduced.
[0166] Referring to FIG. 7D, first, the determination unit 132
stands by a change in the number of secondary systems (step S110).
Subsequently, when the number of secondary systems changes, the
process proceeds to step S115.
[0167] Next, the determination unit 132 determines whether the
changed number of secondary systems exceeds the determination
threshold (step S115). If the changed number of secondary systems
does not exceed the determination threshold, the process proceeds
to step S120. On the other hand, if the changed number of secondary
systems exceeds the determination threshold, the process proceeds
to step S135.
[0168] In step S120, the calculation unit 134 recalculates the
nominal transmit power and the interference avoidance margin
according to the power distribution method described in Patent
Literature 1 or the margin minimization method described in
Non-Patent Literature 2 (step S120). Subsequently, the signaling
unit 136 reports the recalculated nominal transmit power and
interference avoidance margin to the wireless communication
apparatus 20 which is the master device of each of the existing
secondary systems and the new secondary systems (step S125). Also,
the calculation unit 132 updates the base value N.sub.WSD of the
number of secondary systems and the maximum aggregated interference
quantity I.sub.Agg,max at the base point in time to the most recent
values (step S130).
[0169] In step S135, the determination unit 132 additionally
compares the absolute value of the variation in the number of
secondary systems to a threshold value (step S135). The threshold
value at this point may be the virtual variation N.sub.WSD_VAR'. In
addition, different threshold values for the case of an increase
and the case of a decrease may be used. If the absolute value of
the variation in the number of secondary systems exceeds the
threshold value, the calculation unit 134 adjusts the interference
avoidance margin by calculating the adjustment of the interference
avoidance margin on the basis of the virtual variation in the
number of secondary systems (step S139). Subsequently, the
signaling unit 136 reports the margin adjustment calculated by the
calculation unit 134 to the wireless communication apparatus 20
which is the master device of each of the existing secondary
systems (step S145). If the absolute value of the variation in the
number of secondary systems does not exceed the threshold value,
these steps S140 and S145 are skipped.
[0170] Furthermore, the calculation unit 134 calculates the nominal
transmit power for the new secondary systems (step S160).
Subsequently, the signaling unit 136 reports the nominal transmit
power, the interference avoidance margin, and the margin adjustment
to the wireless communication apparatus 20 which is the master
device of each of the new secondary systems (step S165).
[0171] After that, during the period until the next calculation
timing arrives, variation in the number of secondary systems is
monitored by the determination unit 132, and the process returns to
step S110 (step S180).
4-2. Margin Adjustment Process
[0172] FIG. 8 is a flowchart illustrating an example of the flow of
a margin adjustment process (corresponding to step S140) which may
be executed during the power distribution process illustrated in
FIGS. 7A to 7C.
[0173] Referring to FIG. 8, first, the calculation unit 134 derives
the estimated interference variation dI on the basis of the
variation N.sub.WSD_VAR in the number of secondary systems (step
S141). Next, the calculation unit 134 acquires the aggregated
interference quantity I.sub.Agg,max at the base point in time from
the storage unit 120 (step S142). Subsequently, the calculation
unit 134 computes the margin adjustment dM by substituting the
variation N.sub.WSD_VAR in the number of secondary systems, the
estimated interference variation dI, and the aggregated
interference quantity I.sub.Agg,max into Expression (7) (step
S143).
[0174] Note that when Expression (9) is used based on the
assumption that the number of secondary systems and the aggregated
interference quantity are proportional, the derivation of the
estimated interference variation dI and the substitution of dI into
the formula may also be omitted.
4-3. Signaling Sequence
[0175] FIGS. 9A and 9B illustrate an example of a signaling
sequence in the communication control system 1 according to an
embodiment. In the sequence of FIG. 9A, the communication control
apparatus 100, a wireless communication apparatus 20a which is the
master device of an existing secondary system, and a wireless
communication apparatus 20h which is the master device of a new
secondary system participate. Note that only the wireless
communication apparatuses 20a and 20h are illustrated herein for
the sake of simplicity, but in actual practice, the communication
control system 1 is assumed to include more wireless communication
apparatuses 20.
[0176] Referring to FIG. 9A, first, the wireless communication
apparatus 20h transmits an activation request to the communication
control apparatus 100 (step S10). Upon receiving the activation
request from the wireless communication apparatus 20h, the
communication control apparatus 100 counts up the number of
secondary systems.
[0177] When a periodic calculation timing arrives, the
communication control apparatus 100 executes the power distribution
process described using FIGS. 7A to 7D (step S15). As a result, the
transmit power that should be allocated to the secondary system is
recalculated, or the previously calculated transmit power is
adjusted on the basis of the variation in the number of secondary
systems.
[0178] The communication control apparatus 100 indicates that
activation is allowed, and also signals the power allocation result
to the wireless communication apparatus 20h (step S20). In
addition, the communication control apparatus 100 signals the power
allocation result or the margin adjustment result to the wireless
communication apparatus 20a (step S20).
[0179] The wireless communication apparatus 20h calculates the
transmit power allocated to the new secondary system by using the
power allocation result indicated by the communication control
apparatus 100 (step S30). Additionally, the wireless communication
apparatus 20h may report the calculated allocated transmit power to
the communication control apparatus 100 (step S35).
[0180] The wireless communication apparatus 20a calculates the
recalculated or adjusted allocated transmit power by using the
power allocation result of the margin adjustment result indicated
by the communication control apparatus 100 (step S40).
Additionally, the wireless communication apparatus 20a may report
the calculated allocated transmit power to the communication
control apparatus 100 (step S45).
[0181] Referring to FIG. 9B, there are illustrated a data server
having the authority to allocate transmit power for a neighboring
region 3b neighboring the geographical region 3a that includes the
communication control apparatus 100, the wireless communication
apparatus 20a, and the wireless communication apparatus 20h, and a
wireless communication apparatus inside the neighboring region
3b.
[0182] In a situation demanding the consideration of the presence
of the secondary system inside the neighboring region 3b, the
number of secondary systems that should be considered is signaled
to the communication control apparatus 100 from the data server
having authority for the neighboring region 3b (step S50). The
number of secondary systems signaled at this point corresponds to
the parameter N.sub.WSD_B in Expression (15) and Expression (16)
discussed earlier, and is treated as a variation in the number of
secondary systems.
[0183] The communication control apparatus 100 executes the power
distribution process using the number .sub.WSD_A of secondary
systems inside the geographical region 3a and the number
N.sub.WSD_B of secondary systems that should be considered inside
the neighboring region 3b (step S55). As a result, the transmit
power that should be allocated to the secondary system is
recalculated, or the previously calculated transmit power is
adjusted on the basis of N.sub.WSD_B.
[0184] The communication control apparatus 100 signals the power
allocation result or the margin adjustment result to the wireless
communication apparatus 20a and the wireless communication
apparatus 20h (steps S60, S65).
[0185] The wireless communication apparatus 20h calculates the
recalculated or adjusted allocated transmit power by using the
power allocation result of the margin adjustment result indicated
by the communication control apparatus 100 (step S70).
Additionally, the wireless communication apparatus 20h may report
the calculated allocated transmit power to the communication
control apparatus 100 (step S75).
[0186] Similarly, the wireless communication apparatus 20a
calculates the recalculated or adjusted allocated transmit power by
using the power allocation result of the margin adjustment result
indicated by the communication control apparatus 100 (step S80).
Additionally, the wireless communication apparatus 20a may report
the calculated allocated transmit power to the communication
control apparatus 100 (step S85).
5. Exemplary Configuration of Wireless Communication Apparatus
[0187] FIG. 10 is a block diagram illustrating an example of a
logical configuration of the wireless communication apparatus 20
according to an embodiment. Referring to FIG. 10, the wireless
communication apparatus 20 includes a wireless communication unit
210, a network communication unit 220, a storage unit 230, and a
communication control unit 240.
(1) Wireless Communication Section
[0188] The wireless communication unit 210 executes wireless
communication with terminal devices positioned nearby (slave
devices of the secondary system) using transmit power allocated by
the communication control apparatus 100. For example, the wireless
communication unit 210 transmits a beacon signal on one of the
frequency channels available for use as indicated by the
communication control apparatus 100. Upon sensing the beacon
signal, a slave device exchanges parameters for the operation and
management of the secondary system with the wireless communication
apparatus 20, and initiates wireless communication. The parameters
exchanged at this point may include parameters for controlling the
transmit power of the slave device (for example, a value of
transmit power).
(2) Network Communication Unit
[0189] The network communication unit 220 establishes backhauling
between the wireless communication apparatus 20 and the
communication control apparatus 100. Subsequently, the network
communication unit 220 receives various signaling messages
transmitted from the communication control apparatus 100 over
backhauling. In addition, the network communication unit 220
transmits secondary system information about the secondary system
operated and managed by the wireless communication apparatus 20 to
the communication control apparatus 100. Note that when the
backhauling is a wireless link, the network communication unit 220
may be omitted from the configuration of the wireless communication
apparatus 20.
(3) Storage Unit
[0190] The storage unit 230 uses a storage medium such as a hard
disk or semiconductor memory to store programs and data for the
operation of the wireless communication apparatus 20. Data stored
by the storage unit 230 may include secondary system information
about the secondary system operated and managed by the wireless
communication apparatus 20, power allocation-related information
indicated by the communication control apparatus 100, and slave
device information, for example.
(4) Communication Control Unit
[0191] The communication control unit 240 controls communication
executed by the wireless communication apparatus 20. For example,
when the wireless communication apparatus 20 starts the operation
and management of the secondary system (or returns from sleep
mode), the communication control unit 240 transmits an activation
request to the communication control apparatus 100 via backhauling.
Subsequently, if power allocation-related information is received
from the communication control apparatus 100, the operating
frequency and transmit power for the wireless communication unit
210 are configured in accordance with the transmit power allocation
by the communication control apparatus 100.
[0192] Consequently, wireless communication becomes possible
between the wireless communication apparatus 20 which acts as the
master device, and one or more slave devices. The maximum transmit
power usable by the wireless communication unit 210 may be
calculated by subtracting the interference avoidance margin (and if
necessary, the signaling reduction margin) from the nominal
transmit power indicated by the communication control apparatus
100. If a signaling message indicating an adjustment of the
interference avoidance margin is received from the communication
control apparatus 100, the communication control unit 240 updates
the configuration of the transmit power in the wireless
communication unit 210 by adding the margin adjustment to the
margin included in the already-configured transmit power. When the
operation and management of the secondary system is stopped (or
transitioned to sleep mode), the communication control unit 240
transmits a deactivation request to the communication control
apparatus 100 via backhauling. Consequently, the communication
control apparatus 100 is able to recognize a decrease in secondary
systems.
6. Another Example of System Model
[0193] FIG. 1 illustrates a system model in which a communication
control apparatus 100 that may correspond to a GLDB is deployed in
the communication control system 1, and in which the communication
control apparatus 100 executes power calculation and signaling with
secondary systems. However, such a system model is merely one
example. For example, the functions of the communication control
apparatus 100 discussed above may also be realized by two or more
hierarchically separated entities.
[0194] FIG. 11 is an explanatory diagram for describing another
example of a system model. Referring to FIG. 11, the communication
control system 2 includes a GLDB 102, one or more white space
databases (WSDBs) 104a, 104b, and so on, one or more master WSDs
20a, 20b, and so on, and one or more slave WSDs. The GLDB 102
includes, from among the functions of the communication control
apparatus 100 discussed earlier, the calculation function primarily
used for power allocation and the function of switching between
power recalculation and adjustment according to the determination
condition discussed earlier. In addition, the GLDB 102 also
includes a function of communicating with other entities, which may
include the WSDBs 104a, 104b, and so on (hereinafter collectively
termed the WSDB 104). When there is a change in the number of
secondary systems inside the geographical region managed by the
GLDB 102 itself, the GLDB 102 recalculates the allocated transmit
power for the secondary systems, or alternatively, adjusts the
interference avoidance margin on the basis of the variation in the
number of secondary systems.
[0195] The WSDB 104 includes a function of acquiring information
indicating the transmit power calculation result from the GLDB 102,
and signaling parameters for specifying the allocated transmit
power of each secondary system to the master device of the relevant
secondary system. In addition, the WSDB 104 also includes a
function of communicating with other entities that may include the
GLDB 102, and a function of communicating with the master WSD 20.
The WSDB 104 may also receive information indicating the transmit
power calculation result from the GLDB 102 directly, or acquire
such information via another WSDB. As an example, the GLDB 102 may
be a server administered by an official or public organization,
whereas the WSDB may be server administered by a for-profit or
non-profit enterprise.
[0196] The GLDB 102 periodically (or non-periodically) calculates
(recalculates/adjusts) the transmit power that should be allocated
to the secondary systems on the basis of primary system information
and secondary system information reported by the WSDB 104.
Subsequently, the GLDB 102 transmits the power allocation-related
information discussed earlier that indicates the calculation result
to the WSDB 104. The power allocation-related information at least
includes a parameter specifying the calculated interference
avoidance margin. The type of the parameter may be an arbitrary
type, such as those described with regards to the signaling unit
136 of the communication control apparatus 100.
[0197] In the first example, the power allocation-related
information is associated with individual secondary systems (or
master WSDs), and may include a system ID or a device ID, for
example. In this case, the WSDB 104 may signal, in response to a
request from the master WSD 20, information corresponding to the ID
of the request source to the master WSD 20. In the second example,
the power allocation-related information is associated with
location (and device attributes such as antenna height). For
example, the geographical region managed by the GLDB 102 is
segmented into a grid, and identification information is assigned
to individual segments. Subsequently, the power allocation-related
information is provided to the WSDB 104 in the form of a table
mapping pairs of a segment and a device attribute (antenna height,
for example) with a margin value. In this case, the WSDB 104 may
signal, in response to a request from the master WSD 20, the margin
value mapped to the pair of the segment where the requesting device
is positioned and the attribute. In either example, the WSDB 104
may also signal the nominal transmit power and the interference
avoidance margin to each master WSD 20. Alternatively, on the basis
of the power allocation-related information, the WSDB 104 may also
calculate the allocated transmit power of individual master WSDs 20
from the nominal transmit power and the interference avoidance
margin (base value and adjustment), and signal parameters for
specifying the calculated allocated transmit power to individual
master WSDs 20. Additionally, the WSDB 104 may also signal to the
master WSD 20 parameters enabling the master WSD 20 to calculate
the nominal transmit power.
[0198] The master WSD 20 corresponds to the wireless communication
apparatus 20 described using FIG. 10. The master WSD 20 includes a
function of communicating with the WSDB 104 having power
allocation-related information that specifies the allocated
transmit power for the secondary system that the master WSD 20
itself operates and manages. The master WSD 20 receives the
signaling of parameters for specifying the allocated transmit power
from the connected WSDB 104, and controls wireless communication
between the master WSD 20 and one or more slave WSDs in accordance
with the allocated transmit power specified using the received
parameters.
7. Application Examples
[0199] The technology of the present disclosure is applicable to
various products. For example, the communication control
apparatuses 100, 102, and 104 may be realized as any type of data
server such as a tower server, a rack server, and a blade server.
The communication control apparatuses 100, 102, and 104 may be a
control module (such as an integrated circuit module fabricated on
a single die, and a card or a blade that is inserted into a slot of
a blade server) mounted on a server.
[0200] As another example, the wireless communication apparatus 20
may also be realized as an evolved Node B (eNB) of any type, such
as a macro eNB, a pico eNB, or a home eNB. Conversely, the wireless
communication apparatus 20 may also be realized as another type of
base station, such as a NodeB or a base transceiver station
(BTS).
[0201] For example, the wireless communication apparatus 20 may be
realized as a mobile terminal such as a smartphone, a tablet
personal computer (PC), a notebook PC, a portable game terminal, a
portable/dongle type mobile router, and a digital camera, or an
in-vehicle terminal such as a car navigation apparatus. The
wireless communication apparatus 20 may also be realized as a
terminal (that is also referred to as a machine type communication
(MTC) terminal) that performs machine-to-machine (M2M)
communication. Furthermore, the wireless communication apparatus 20
may be a radio communication module (such as an integrated circuit
module fabricated on a single die) mounted on each of the
terminals.
7-1. Application Example Related to Networking Control Node
[0202] FIG. 12 is a block diagram illustrating an example of the
schematic configuration of a GLDB 700 to which the technology of
the present disclosure may be applied. The GLDB 700 includes a
processor 701, a memory 702, a storage 703, a network interface
704, and a bus 706.
[0203] The processor 701 may be, for example, a central processing
unit (CPU) or a digital signal processor (DSP), and controls
functions of the server 700. The memory 702 includes a random
access memory (RAM) and a read only memory (ROM), and stores a
program that is executed by the processor 701 and data. The storage
703 may include a storage medium such as a semiconductor memory and
a hard disk.
[0204] The network interface 704 is a wired communication interface
for connecting the GLDB 700 to a wired communication network 705.
The wired communication network 705 may be a core network such as
an evolved packet core (EPC), or a packet data network (PDN) such
as the Internet.
[0205] The bus 706 connects the processor 701, the memory 702, the
storage 703, and the network interface 704 to each other. The bus
706 may include two or more buses (such as a high speed bus and a
low speed bus) each of which has different speed.
[0206] In the GLDB 700 illustrated in FIG. 12, the control unit 130
described using FIG. 6 may be implemented in the processor 701. For
example, the processor 701 functions as the determination unit 132,
the calculation unit 134, and the signaling unit 136, and thereby
is able to track variation in the number of secondary systems
within the geographical region managed by the GLDB 700 to allocate
transmit power to each secondary system promptly while also
preventing harmful interference on the primary system.
7-2. Application Examples Related to Base Station
[0207] FIG. 13 is a block diagram illustrating an example of the
schematic configuration of an eNB to which the technology of the
present disclosure may be applied. An eNB 800 includes one or more
antennas 810 and a base station apparatus 820. Each antenna 810 and
the base station apparatus 820 may be connected to each other via
an RF cable.
[0208] Each of the antennas 810 includes a single or multiple
antenna elements (such as multiple antenna elements included in an
MIMO antenna), and is used for the base station apparatus 820 to
transmit and receive radio signals. The eNB 800 may include the
multiple antennas 810, as illustrated in FIG. 13. For example, the
multiple antennas 810 may be compatible with multiple frequency
bands used by the eNB 800, respectively. Note that FIG. 13
illustrates the example in which the eNB 800 includes the multiple
antennas 810, but the eNB 800 may also include a single antenna
810.
[0209] The base station apparatus 820 includes a controller 821, a
memory 822, a network interface 823, and a radio communication
interface 825.
[0210] The controller 821 may be, for example, a CPU or a DSP, and
operates various functions of a higher layer of the base station
apparatus 820. For example, the controller 821 generates a data
packet from data in signals processed by the radio communication
interface 825, and transfers the generated packet via the network
interface 823. The controller 821 may bundle data from multiple
base band processors to generate the bundled packet and transfer
the generated bundled packet. The controller 821 may have logical
functions of performing control such as radio resource control,
radio bearer control, mobility management, admission control, and
scheduling. The control may be performed in corporation with an eNB
or a core network node in the vicinity. The memory 822 includes a
RAM and a ROM, and stores a program that is executed by the
controller 821, and various types of control data (such as a
terminal list, transmission power data, and scheduling data).
[0211] The network interface 823 is a communication interface for
connecting the base station apparatus 820 to the wired
communication network 705. The controller 891 may communicate with
the GLDB 700 via the network interface 823.
[0212] The radio communication interface 825 supports any cellular
communication scheme such as long term evolution (LTE) and
LTE-Advanced, and provides radio connection to a terminal (a slave
device) positioned in a cell of the eNB 800 via the antenna 810.
The radio communication interface 825 may typically include, for
example, a baseband (BB) processor 826 and an RF circuit 827. The
BB processor 826 may perform, for example, encoding/decoding,
modulating/demodulating, and multiplexing/demultiplexing, and
performs various types of signal processing of layers (such as L1,
medium access control (MAC), radio link control (RLC), and a packet
data convergence protocol (PDCP)). The BB processor 826 may have a
part or all of the above-described logical functions instead of the
controller 821. The BB processor 826 may be a memory that stores a
communication control program, or a module that includes a
processor and a related circuit configured to execute the program.
Updating the program may allow the functions of the BB processor
826 to be changed. The module may be a card or a blade that is
inserted into a slot of the base station apparatus 820.
Alternatively, the module may also be a chip that is mounted on the
card or the blade. Meanwhile, the RF circuit 827 may include, for
example, a mixer, a filter, and an amplifier, and transmits and
receives radio signals via the antenna 810.
[0213] The radio communication interface 825 may include the
multiple BB processors 826, as illustrated in FIG. 13. For example,
the multiple BB processors 826 may be compatible with multiple
frequency bands used by the eNB 800. The radio communication
interface 825 may include the multiple RF circuits 827, as
illustrated in FIG. 13. For example, the multiple RF circuits 827
may be compatible with multiple antenna elements, respectively.
Note that FIG. 13 illustrates the example in which the radio
communication interface 825 includes the multiple BB processors 826
and the multiple RF circuits 827, but the radio communication
interface 825 may also include a single BB processor 826 or a
single RF circuit 827.
[0214] In the eNB 800 illustrated in FIG. 13, the communication
control unit 240 described using FIG. 10 may be implemented in the
radio communication interface 825. Also, at least some of the
functions may also be implemented in the controller 821. For
example, by executing wireless communication with slave devices
using transmit power allocated by the communication control
apparatus 100, the eNB 800 is able to initiate the management and
operation of a secondary system promptly while also preventing
harmful interference on the primary system.
[0215] (Second Application Example)
[0216] FIG. 14 is a block diagram illustrating an example of the
schematic configuration of a smartphone 900 to which the technology
of the present disclosure may be applied. The smartphone 900
includes a processor 901, a memory 902, a storage 903, an external
connection interface 904, a camera 906, a sensor 907, a microphone
908, an input device 909, a display device 910, a speaker 911, a
radio communication interface 912, one or more antenna switches
915, one or more antennas 916, a bus 917, a battery 918, and an
auxiliary controller 919.
[0217] The processor 901 may be, for example, a CPU or a system on
chip (SoC), and controls functions of an application layer and
another layer of the smartphone 900. The memory 902 includes RAM
and ROM, and stores a program that is executed by the processor
901, and data. The storage 903 may include a storage medium such as
a semiconductor memory and a hard disk. The external connection
interface 904 is an interface for connecting an external device
such as a memory card and a universal serial bus (USB) device to
the smartphone 900.
[0218] The camera 906 includes an image sensor such as a charge
coupled device (CCD) and a complementary metal oxide semiconductor
(CMOS), and generates a captured image. The sensor 907 may include
a group of sensors such as a measurement sensor, a gyro sensor, a
geomagnetic sensor, and an acceleration sensor. The microphone 908
converts sounds that are input to the smartphone 900 to audio
signals. The input device 909 includes, for example, a touch sensor
configured to detect touch onto a screen of the display device 910,
a keypad, a keyboard, a button, or a switch, and receives an
operation or an information input from a user. The display device
910 includes a screen such as a liquid crystal display (LCD) and an
organic light-emitting diode (OLED) display, and displays an output
image of the smartphone 900. The speaker 911 converts audio signals
that are output from the smartphone 900 to sounds.
[0219] The radio communication interface 912 supports any cellular
communication scheme such as LTE and LTE-A, and performs radio
communication. The radio communication interface 912 may typically
include, for example, a BB processor 913 and an RF circuit 914. The
BB processor 913 may perform, for example, encoding/decoding,
modulating/demodulating, and multiplexing/demultiplexing, and
performs various types of signal processing for radio
communication. Meanwhile, the RF circuit 914 may include, for
example, a mixer, a filter, and an amplifier, and transmits and
receives radio signals via the antenna 916. The radio communication
interface 912 may also be a one chip module that has the BB
processor 913 and the RF circuit 914 integrated thereon. The radio
communication interface 912 may include the multiple BB processors
913 and the multiple RF circuits 914, as illustrated in FIG. 14.
Note that FIG. 14 illustrates the example in which the radio
communication interface 912 includes the multiple BB processors 913
and the multiple RF circuits 914, but the radio communication
interface 912 may also include a single BB processor 913 or a
single RF circuit 914.
[0220] Furthermore, in addition to a cellular communication scheme,
the radio communication interface 912 may support another type of
radio communication scheme such as a short-distance wireless
communication scheme, a near field communication scheme, and a
radio local area network (LAN) scheme. In that case, the radio
communication interface 912 may include the BB processor 913 and
the RF circuit 914 for each radio communication scheme.
[0221] Each of the antenna switches 915 switches connection
destinations of the antennas 916 among multiple circuits (such as
circuits for different radio communication schemes) included in the
radio communication interface 912.
[0222] Each of the antennas 916 includes a single or multiple
antenna elements (such as multiple antenna elements included in an
MIMO antenna), and is used for the radio communication interface
912 to transmit and receive radio signals. The smartphone 900 may
include the multiple antennas 916, as illustrated in FIG. 14. Note
that FIG. 14 illustrates the example in which the smartphone 900
includes the multiple antennas 916, but the smartphone 900 may also
include a single antenna 916.
[0223] Furthermore, the smartphone 900 may include the antenna 916
for each radio communication scheme. In that case, the antenna
switches 915 may be omitted from the configuration of the
smartphone 900.
[0224] The bus 917 connects the processor 901, the memory 902, the
storage 903, the external connection interface 904, the camera 906,
the sensor 907, the microphone 908, the input device 909, the
display device 910, the speaker 911, the radio communication
interface 912, and the auxiliary controller 919 to each other. The
battery 918 supplies power to blocks of the smartphone 900
illustrated in FIG. 14 via feeder lines, which are partially shown
as dashed lines in the figure. The auxiliary controller 919
operates a minimum necessary function of the smartphone 900, for
example, in a sleep mode.
[0225] The smartphone 900 illustrated in FIG. 14 may also operate
as the master device of a secondary system. In this case, the
communication control unit 240 described using FIG. 10 may be
implemented in the radio communication interface 912. Also, at
least some of these functions may also be implemented in the
processor 901 or the auxiliary controller 919. For example, by
executing wireless communication with slave devices using transmit
power allocated by the communication control apparatus 100, the
smartphone 900 is able to initiate the management and operation of
a secondary system promptly while also preventing harmful
interference on the primary system. Additionally, the smartphone
900 may also operate as a slave device of a secondary system.
Third Application Example
[0226] FIG. 15 is a block diagram illustrating an example of the
schematic configuration of a car navigation apparatus 920 to which
the technology of the present disclosure may be applied. The car
navigation apparatus 920 includes a processor 921, a memory 922, a
global positioning system (GPS) module 924, a sensor 925, a data
interface 926, a content player 927, a storage medium interface
928, an input device 929, a display device 930, a speaker 931, a
radio communication interface 933, one or more antenna switches
936, one or more antennas 937, and a battery 938.
[0227] The processor 921 may be, for example, a CPU or a SoC, and
controls a navigation function and another function of the car
navigation apparatus 920. The memory 922 includes a RAM and a ROM,
and stores a program that is executed by the processor 921, and
data.
[0228] The GPS module 924 uses GPS signals received from a GPS
satellite to measure a position (such as latitude, longitude, and
altitude) of the car navigation apparatus 920. The sensor 925 may
include a group of sensors such as a gyro sensor, a geomagnetic
sensor, and an air pressure sensor. The data interface 926 is
connected to, for example, an in-vehicle network 941 via a terminal
that is not shown, and acquires data generated by the vehicle, such
as vehicle speed data.
[0229] The content player 927 reproduces content stored in a
storage medium (such as a CD and a DVD) that is inserted into the
storage medium interface 928. The input device 929 includes, for
example, a touch sensor configured to detect touch onto a screen of
the display device 930, a button, or a switch, and receives an
operation or an information input from a user. The display device
930 includes a screen such as a LCD or an OLED display, and
displays an image of the navigation function or content that is
reproduced. The speaker 931 outputs sound of the navigation
function or the content that is reproduced.
[0230] The radio communication interface 933 supports any cellular
communication scheme such as LET and LTE, and performs radio
communication. The radio communication interface 933 may typically
include, for example, a BB processor 934 and an RF circuit 935. The
BB processor 934 may perform, for example, encoding/decoding,
modulating/demodulating, and multiplexing/demultiplexing, and
performs various types of signal processing for radio
communication. Meanwhile, the RF circuit 935 may include, for
example, a mixer, a filter, and an amplifier, and transmits and
receives radio signals via the antenna 937. The radio communication
interface 933 may be a one chip module having the BB processor 934
and the RF circuit 935 integrated thereon. The radio communication
interface 933 may include the multiple BB processors 934 and the
multiple RF circuits 935, as illustrated in FIG. 15. Note that FIG.
15 illustrates the example in which the radio communication
interface 933 includes the multiple BB processors 934 and the
multiple RF circuits 935, but the radio communication interface 933
may also include a single BB processor 934 or a single RF circuit
935.
[0231] Furthermore, in addition to a cellular communication scheme,
the radio communication interface 933 may support another type of
radio communication scheme such as a short-distance wireless
communication scheme, a near field communication scheme, and a
radio LAN scheme. In that case, the radio communication interface
933 may include the BB processor 934 and the RF circuit 935 for
each radio communication scheme.
[0232] Each of the antenna switches 936 switches connection
destinations of the antennas 937 among multiple circuits (such as
circuits for different radio communication schemes) included in the
radio communication interface 933.
[0233] Each of the antennas 937 includes a single or multiple
antenna elements (such as multiple antenna elements included in an
MIMO antenna), and is used for the radio communication interface
933 to transmit and receive radio signals. The car navigation
apparatus 920 may include the multiple antennas 937, as illustrated
in FIG. 15. Note that FIG. 15 illustrates the example in which the
car navigation apparatus 920 includes the multiple antennas 937,
but the car navigation apparatus 920 may also include a single
antenna 937.
[0234] Furthermore, the car navigation apparatus 920 may include
the antenna 937 for each radio communication scheme. In that case,
the antenna switches 936 may be omitted from the configuration of
the car navigation apparatus 920.
[0235] The battery 938 supplies power to blocks of the car
navigation apparatus 920 illustrated in FIG. 15 via feeder lines
that are partially shown as dashed lines in the figure. The battery
938 accumulates power supplied form the vehicle.
[0236] The car navigation apparatus 920 illustrated in FIG. 15 may
also operate as the master device of a secondary system. In this
case, the communication control unit 240 described using FIG. 10
may be implemented in the radio communication interface 933. Also,
at least some of these functions may also be implemented in the
processor 921. For example, by executing wireless communication
with slave devices using transmit power allocated by the
communication control apparatus 100, the car navigation apparatus
920 is able to initiate the management and operation of a secondary
system promptly while also preventing harmful interference on the
primary system. Additionally, the car navigation apparatus 920 may
also operate as a slave device of a secondary system.
[0237] The technology of the present disclosure may also be
realized as an in-vehicle system (or a vehicle) 940 including one
or more blocks of the car navigation apparatus 920, the in-vehicle
network 941, and a vehicle-side module 942. The vehicle-side module
942 generates vehicle data such as vehicle speed, engine speed, and
trouble information, and outputs the generated data to the
in-vehicle network 941.
8. Conclusion
[0238] The foregoing thus describes several embodiments of
technology according to the present disclosure in detail using
FIGS. 1 to 15. According to the foregoing embodiments, in an
apparatus that calculates the transmit power that should be
allocated to one or more secondary systems that secondarily use
frequency channels protected for a primary system, when the number
of secondary systems changes, whether to recalculate the transmit
power or adjust a previously calculated transmit power on the basis
of the variation in the number of secondary systems is determined
dynamically in accordance with a condition dependent on the number
of secondary systems. Consequently, it is possible to achieve both
prevention of harmful interference and promptness of power
allocation. In addition, it is possible to resolve adverse effects,
such as the production of harmful interference caused by power
allocation not being updated in a timely manner. Consequently, the
utilization efficiency of radio resources is improved. Note that
although this specification describes an example in which primarily
the recalculation and adjustment of transmit power is conducted
periodically, the technology according to the present disclosure is
not limited to such an example. For example, the transmit power may
also be adjusted with a small calculation cost in accordance with
the technology of the present disclosure when a trigger is
detected, such as a request from the primary system or a secondary
system, or a change in some kind of input condition.
[0239] For example, the transmit power is recalculated when the
changed number of secondary systems falls below a threshold. On the
other hand, adjustment of a previously calculated transmit power is
executed when the changed number of secondary systems exceeds a
threshold. Consequently, when many secondary systems are present,
and there is a possibility that the calculation of power allocation
may not finish within an allowed time, only adjustment of the
transmit power is executed with a simple algorithm. Consequently,
it is possible to prevent the loss of communication opportunities
in a secondary system caused by a delay in the allocation of
transmit power, while also maintaining the protection of the
primary system.
[0240] According to a power calculation model given as an example,
the transmit power to allocate to each secondary system is
calculated by using a nominal transmit power of the relevant
secondary system and an interference avoidance margin. In this
model, the adjustment of transmit power is executed by adjusting
the interference avoidance margin on the basis of the variation in
the number of secondary systems. Consequently, the transmit power
may be adjusted with a small calculation cost, simply by monitoring
changes in the number of secondary systems.
[0241] Note that the series of control processing by the respective
apparatuses described herein may be implemented by using any of
software, hardware, and a combination of software and hardware.
Programs constituting the software are previously stored in, for
example, a recording medium (a non-transitory medium) provided in
the inside or the outside of the respective apparatuses. And the
respective programs are, for example, read into a random access
memory (RAM) during execution and executed by the processor such as
the CPU.
[0242] Further, the processes described using the flowcharts in the
present description may not necessarily be executed in the order
indicated by the flowchart. Some process steps may be executed in
parallel. Further, additional process steps may be employed, and
some process steps may be omitted.
[0243] The preferred embodiment(s) of the present disclosure
has/have been described above with reference to the accompanying
drawings, whilst the present disclosure is not limited to the above
examples. A person skilled in the art may find various alterations
and modifications within the scope of the appended claims, and it
should be understood that they will naturally come under the
technical scope of the present disclosure.
[0244] In addition, the effects described in the present
specification are merely illustrative and demonstrative, and not
limitative. In other words, the technology according to the present
disclosure can exhibit other effects that are evident to those
skilled in the art along with or instead of the effects based on
the present specification.
[0245] Additionally, the present technology may also be configured
as below.
(1)
[0246] A communication control apparatus including:
[0247] a calculation unit configured to calculate a transmit power
to be allocated to one or more secondary systems that secondarily
use frequency channels protected for a primary system; and
[0248] a determination unit configured to, when the number of
secondary systems changes, determine, according to a condition
dependent on the number of secondary systems, whether to cause the
calculation unit to recalculate the transmit power or adjust a
previously calculated transmit power on the basis of the variation
in the number of secondary systems.
(2)
[0249] The communication control apparatus according to (1),
wherein
[0250] the determination unit causes the calculation unit to
recalculate the transmit power in a case of the changed number of
secondary systems falling below a threshold value, and causes the
calculation unit to adjust the previously calculated transmit power
in a case of the changed number of secondary systems exceeding the
threshold value.
(3)
[0251] The communication control apparatus according to (2),
wherein
[0252] the threshold value is configured in advance in a manner
that an estimated calculation time dependent on the number of
secondary systems does not exceed an allowed calculation time.
(4)
[0253] The communication control apparatus according to (2),
wherein
[0254] the threshold value is configured dynamically in a manner
that an estimated calculation time dependent on the number of
secondary systems does not exceed an allowed calculation time.
(5)
[0255] The communication control apparatus according to any one of
(1) to (4), wherein
[0256] the variation in the number of secondary systems is
calculated on a basis of the number of secondary systems at a point
in time when the transmit power was last recalculated.
(6)
[0257] The communication control apparatus according to any one of
(1) to (4), wherein
[0258] the variation in the number of secondary systems is
calculated on a basis of the number of secondary systems at an
immediately previous point in time when the transmit power was
recalculated or adjusted.
(7)
[0259] The communication control apparatus according to any one of
(1) to (6), wherein
[0260] the transmit power to be allocated to each secondary system
includes a nominal transmit power of the relevant secondary system
and a margin for interference avoidance, and
[0261] the calculation unit adjusts the transmit power by adjusting
the margin for interference avoidance on the basis of the variation
in the number of secondary systems.
(8)
[0262] The communication control apparatus according to (7),
wherein
[0263] the calculation unit calculates an adjustment of the margin
for interference avoidance by estimating a variation in an
interference quantity on a basis of the variation in the number of
secondary systems.
(9)
[0264] The communication control apparatus according to (8),
wherein
[0265] the calculation unit estimates the variation in the
interference quantity by using a table defining mappings between
the variation in the number of secondary systems and the variation
in the interference quantity.
(10)
[0266] The communication control apparatus according to (8),
wherein
[0267] the calculation unit estimates the variation in the
interference quantity on a basis of an assumption that the number
of secondary systems and the interference quantity are
proportional.
(11)
[0268] The communication control apparatus according to any one of
(7) to (10), further including
[0269] a signaling unit configured to signal an adjustment of the
margin for interference avoidance calculated by the calculation
unit to existing secondary systems.
(12)
[0270] The communication control apparatus according to (11),
wherein
[0271] the signaling unit signals a base value and the adjustment
of the margin for interference avoidance to new secondary
systems.
(13)
[0272] The communication control apparatus according to (12),
wherein
[0273] depending on the load on the calculation unit, the signaling
unit causes each relevant secondary system itself to calculate the
nominal transmit power by signaling calculation parameters to the
new secondary systems.
(14)
[0274] The communication control apparatus according to any one of
(1) to (13), wherein
[0275] the communication control apparatus has an authority to
allocate transmit power to the one or more secondary systems within
a first geographical region, and
[0276] the calculation unit, in a case in which presence of
secondary systems within a second geographical region neighboring
the first geographical region should be considered in transmit
power allocation, acquires information indicating a number of
secondary systems within the second geographical region that should
be considered from another apparatus having authority for the
second geographical region.
(15)
[0277] The communication control apparatus according to any one of
(11) to (13), wherein
[0278] the transmit power to be allocated to each secondary system
additionally includes a margin for reducing signaling overhead,
and
[0279] the signaling unit refrains from signaling the adjustment of
the margin for interference avoidance to the existing secondary
systems in a case of the adjustment of the margin for interference
avoidance falling below the margin for reducing signaling overhead
included in an already-allocated transmit power.
(16)
[0280] The communication control apparatus according to any one of
(1) to (15), wherein
[0281] the calculation unit reduces the frequency of signaling to
each secondary system by adjusting the transmit power by setting
the variation in the number of secondary systems to a
greater-than-actual virtual value.
(17)
[0282] A communication control method including:
[0283] in a processor, calculating a transmit power to be allocated
to one or more secondary systems that secondarily use frequency
channels protected for a primary system; and
[0284] when the number of secondary systems changes, determining,
according to a condition dependent on the number of secondary
systems, whether to cause the processor to recalculate the transmit
power or adjust a previously calculated transmit power on the basis
of the variation in the number of secondary systems.
(18)
[0285] A wireless communication apparatus including:
[0286] a communication unit configured to communicate with a
communication control apparatus that, when there is a change in the
number of secondary systems operated and managed by secondarily
using frequency channels protected for a primary system,
recalculates a transmit power to be allocated to each secondary
system or adjusts a previously calculated transmit power on the
basis of the variation in the number of secondary systems,
according to a condition depending on the number of secondary
systems; and
[0287] a communication control unit configured to control wireless
communication between the wireless communication apparatus and one
or more terminal apparatuses according to the allocation of
transmit power indicated by the communication control apparatus via
the communication unit.
[0288] Additionally, the present technology may also be configured
as below.
(1)
[0289] A communication control apparatus including:
[0290] a calculation unit configured to calculate a transmit power
to be allocated, including a nominal transmit power and a margin
for interference avoidance, for one or more secondary systems that
secondarily use frequency channels protected for a primary system;
and
[0291] a determination unit configured to determine a variation in
a number of secondary systems, and cause the calculation unit to
adjust the margin for interference avoidance on a basis of the
determined variation.
(2)
[0292] The communication control apparatus according to (1),
wherein
[0293] the determination unit determines, according to a condition
dependent on the number of secondary systems, whether to cause the
calculation unit to recalculate the transmit power or adjust a
previously calculated transmit power by adjusting the margin for
interference avoidance on a basis of the variation.
(3)
[0294] The communication control apparatus according to (2),
wherein
[0295] the determination unit causes the calculation unit to
recalculate the transmit power in a case of the changed number of
secondary systems falling below a threshold value, and causes the
calculation unit to adjust the previously calculated transmit power
in a case of the changed number of secondary systems exceeding the
threshold value.
(4)
[0296] The communication control apparatus according to (3),
wherein
[0297] the threshold value is configured in advance in a manner
that an estimated calculation time dependent on the number of
secondary systems does not exceed an allowed calculation time.
(5)
[0298] The communication control apparatus according to (3),
wherein
[0299] the threshold value is configured dynamically in a manner
that an estimated calculation time dependent on the number of
secondary systems does not exceed an allowed calculation time.
(6)
[0300] The communication control apparatus according to any one of
(2) to (5), wherein
[0301] the variation in the number of secondary systems is
calculated on a basis of the number of secondary systems at a point
in time when the transmit power was last recalculated.
(7)
[0302] The communication control apparatus according to any one of
(2) to (5), wherein
[0303] the variation in the number of secondary systems is
calculated on a basis of the number of secondary systems at an
immediately previous point in time when the transmit power was
recalculated or adjusted.
(8)
[0304] The communication control apparatus according to any one of
(1) to (7), wherein
[0305] the number of secondary systems is based on one or both of a
number of master devices and a number of slave devices in the
secondary systems.
(9)
[0306] The communication control apparatus according to (8),
wherein
[0307] the numbers of devices are calculated by including weights
depending on a device configuration.
(10)
[0308] The communication control apparatus according to any one of
(2) to (7), wherein
[0309] the determination unit additionally determines whether to
cause the calculation unit to recalculate the transmit power or
adjust the previously calculated transmit power according to a
condition dependent on at least one from among a reference point, a
frequency channel to be secondarily used, a device antenna height,
and an interference level from other systems.
(11)
[0310] The communication control apparatus according to any one of
(1) to (10), wherein
[0311] the calculation unit calculates an adjustment of the margin
for interference avoidance by estimating a variation in an
interference quantity on a basis of the variation in the number of
secondary systems.
(12)
[0312] The communication control apparatus according to (11),
wherein
[0313] the calculation unit estimates the variation in the
interference quantity by using a table defining mappings between
the variation in the number of secondary systems and the variation
in the interference quantity.
(13)
[0314] The communication control apparatus according to (11),
wherein
[0315] the calculation unit estimates the variation in the
interference quantity on a basis of an assumption that the number
of secondary systems and the interference quantity are
proportional.
(14)
[0316] The communication control apparatus according to any one of
(1) to (13), wherein
[0317] the communication control apparatus has an authority to
allocate transmit power to the one or more secondary systems within
a first geographical region, and
[0318] the calculation unit, in a case in which presence of
secondary systems within a second geographical region neighboring
the first geographical region should be considered in transmit
power allocation, acquires information indicating a number of
secondary systems within the second geographical region that should
be considered from another apparatus having authority for the
second geographical region.
(15)
[0319] The communication control apparatus according to any one of
(1) to (14), wherein
[0320] the calculation unit adjusts the margin for interference
avoidance by setting the variation in the number of secondary
systems to a greater-than-actual virtual value.
(16)
[0321] The communication control apparatus according to any one of
(1) to (15), further including
[0322] a signaling unit configured to signal an adjustment of the
margin for interference avoidance calculated by the calculation
unit for the secondary systems.
(17)
[0323] The communication control apparatus according to (16),
wherein
[0324] the allocated transmit power for each secondary system
additionally includes a margin for reducing signaling overhead,
and
[0325] the signaling unit refrains from signaling the adjustment of
the margin for interference avoidance in a case of the adjustment
of the margin for interference avoidance falling below the margin
for reducing signaling overhead included in an already-allocated
transmit power.
(18)
[0326] A communication control method including:
[0327] in a processor, calculating a transmit power to be
allocated, including a nominal transmit power and a margin for
interference avoidance, for one or more secondary systems that
secondarily use frequency channels protected for a primary system;
and
[0328] determining a variation in a number of secondary systems,
and causing the processor to adjust the margin for interference
avoidance on a basis of the determined variation.
(19)
[0329] A communication control apparatus including:
[0330] a communication unit configured to communicate with a master
device of one or more secondary systems that secondarily use
frequency channels protected for a primary system; and
[0331] a control unit configured to signal, on a basis of
information acquired from a data server that calculates an
allocated transmit power for the secondary systems including a
nominal transmit power and a margin for interference avoidance
adjusted on a basis of variation in a number of secondary systems,
parameters for specifying the allocated transmit power to the
master device via the communication unit.
(20)
[0332] The communication control apparatus according to (19),
wherein
[0333] the control unit calculates the allocated transmit power for
each master device from the nominal transmit power as well as a
base value and an adjustment of the margin for interference
avoidance, and signals the parameters for specifying the calculated
allocated transmit power to the master device.
(21)
[0334] The communication control apparatus according to (19),
wherein
[0335] the parameters include parameters for calculating the
nominal transmit power.
(22)
[0336] A communication control method of a communication control
apparatus that communicates with a master device of one or more
secondary systems that secondarily use frequency channels protected
for a primary system, the communication control method
including
[0337] signaling, on a basis of information acquired from a data
server that calculates an allocated transmit power for the
secondary systems including a nominal transmit power and a margin
for interference avoidance adjusted on a basis of variation in a
number of secondary systems, parameters for specifying the
allocated transmit power to the master device.
(23)
[0338] A wireless communication apparatus that operates and manages
a secondary system that secondarily uses a frequency channel
protected for a primary system, the wireless communication
apparatus including:
[0339] a communication unit configured to receive signaling of
parameters for specifying an allocated transmit power based on
information acquired from a data server that calculates the
allocated transmit power for the secondary system including a
nominal transmit power and a margin for interference avoidance
adjusted on a basis of variation in a number of secondary systems;
and
[0340] a communication control unit configured to control wireless
communication between the wireless communication apparatus and one
or more terminal apparatuses according to the allocated transmit
power specified using the parameters.
(24)
[0341] A communication control method of a wireless communication
apparatus that operates and manages a secondary system that
secondarily uses a frequency channel protected for a primary
system, the communication control method including:
[0342] receiving signaling of parameters for specifying an
allocated transmit power based on information acquired from a data
server that calculates the allocated transmit power for the
secondary system including a nominal transmit power and a margin
for interference avoidance adjusted on a basis of variation in a
number of secondary systems; and
[0343] controlling wireless communication between the wireless
communication apparatus and one or more terminal apparatuses
according to the allocated transmit power specified using the
parameters.
REFERENCE SIGNS LIST
[0344] 1, 2 communication control system [0345] 10 primary
transceiver [0346] 100 communication control apparatus (GLDB)
[0347] 102 communication control apparatus (GLDB) [0348] 104
communication control apparatus (WSDB) [0349] 110 communication
unit [0350] 120 storage unit [0351] 130 control unit [0352] 132
determination unit [0353] 134 calculation unit [0354] 136 signaling
unit [0355] 20 wireless communication apparatus (master WSD) [0356]
210 wireless communication unit [0357] 220 network communication
unit [0358] 230 storage unit [0359] 240 communication control
unit
* * * * *